TOC Application Handbook
1.
Environmental Analysis
1.1. TOC determination in drinking water
1.2. TOC determination in wastewater
1.3. TOC determination in surface water and groundwater
1.4. TOC determination in seawater
1.5. TOC determination in solid samples using the suspension method
1.6. TOC determination in particle-containing samples – Cellulose test according EN 1484
1.7. Determination of particulate organic after filtration (glass fiber suspension)
2.
Pharmaceutical Industry
2.1. TOC determination in ultrapure water – comparison of the various oxidation techniques
2.2. TOC determination in cleaning validation – Final Rinse
2.3. TOC determination in cleaning validation – SWAB Method
2.4. TOC determination according to EP 2.2.44
3.
Chemical Industry
3.1. TOC determination
3.2. TOC determination
3.3. TOC determination
3.4. TOC determination
3.5. TOC determination
3.6. TOC determination
3.7. TOC determination
3.8. TOC determination
in
in
in
in
in
in
in
in
hydrochloric acid
nitric acid
sulfuric acid
brine solution
sodium hydroxide solution
soda solution
ammonia or ammonium salt solution
sodium nitrate and sodium nitrite
4.
TOC
4.1.
4.2.
4.3.
special application
TOC determination in algal biomass – suspension method
TOC-Determination in liquid manure and fermentation fluids – suspension method
Carbon dioxide determination in beer
5.
TOC
5.1.
5.2.
5.3.
5.4.
5.5.
5.6.
5.7.
5.8.
5.9.
in daily practice
TOC determination methods according to EN 1484
Determination of the purgeable organic carbon (POC)
TNb – total bound nitrogen
Kit for high-salt samples
Kit for small sample volumes
Kit for manual injections
Calibration with automatic dilution function
Blank value consideration in TOC analysis
TOC – Measurement principle – catalytic combustion at 680°C
6.
TOC
6.1.
6.2.
6.3.
6.4.
process analysis
Continuous TOC/TN determination in wastewater treatment plants
TOC process analysis in the paper industry
Continuous TOC determination in the chemical industry
Continuous condensate monitoring using the TOC-4200
1. Environmental analysis
A clean environment is the basis for a
healthy life. Whether water, soil or air –
keeping the environment clean for the
protection of all creatures should be the
primary responsibility of any society. In
Europe alone, there are numerous laws,
ordinances and administrative regulations describing the environmental conditions needed to ensure a certain environmental standard. Instrumental analysis is a useful tool to measure the status
of environmental conditions.
Looking at the numbers of possible
chemical contaminations (compounds),
the group of organic compounds is the
largest. With an estimated number of
more than 19 million, it is impossible to
detect and quantify each and every one
of them.
The sum parameter TOC (Total Organic
Carbon) is one of the most important
parameters used in many environmental
applications. TOC analysis enables the
determination of the sum of all organically bound carbons in the abovementioned organic compounds and is,
therefore, a measure of organic pollution in a matrix.
The relevance of the TOC parameter
becomes clear when looking at the
parameter lists of various regulations in
European countries: the Waste Disposal
Ordinance, the Waste Technical Guidelines, the Landfill Ordinance, the Ordinance pertaining to the Recovery of
Waste, the Stowing Directive, the Drinking Water Ordinance and the Wastewater Ordinance are just some that
mention TOC as a valuable parameter.
TOC analysis is therefore carried out in a
wide variety of environmental matrices:
from groundwater to seawater, from
drinking water to wastewater, from soils
to sewage sludge. The diversity in environmental applications creates many
different challenges for the analytical
systems being used. In addition to the
different concentration ranges, TOC
analysis repeatedly faces different types
of conditions such as salt content or
number of particles.
Shimadzu offers various solutions for
these different applications. The TOC-L
family is module-based. Two basic analyzer types can be equipped with many
options, kits and numerous accessories
and customized to any particular application. This makes the TOC-L one of the
most universal TOC analyzers.
Further details can be found in the individual application notes (for instance
‘TOC determination in drinking water,
wastewater or suspensions’).
In addition to environmental analysis,
there are also application notes and
information on ‘Pharmaceutical industry’, ‘Chemical Industry’, ‘TOC special
applications’, ‘TOC in daily practice’ and
‘TOC process analysis.’
Sum parameter – Total Organic Carbon
TOC –Determination in drinking water
No. SCA-130-101
Drinking water is one of the main important
and life-sustaining food stuffs and is essential
to the survival of all known organism. It is a
crucial component for metabolic processes
and serves as solvent for many bodily
solutes. Water for human consumption must
be free from pathogens, pleasant to drink and
pure. Continuous monitoring is carried out
according to European Drinking Water
Regulation to ensure the greatest possible
security
■ European Drinking Water Directive
The Directive is intended to protect human
health by laying down healthiness and purity
requirements which must be met by drinking
water within the European Union (EU).
The directive applies to all water intended for
human consumption apart from natural
mineral waters and water which are medicinal
products.
The European drinking water directive
includes the category of indicator parameter
value specifications. These are not directly
linked to health problems but have an
indicator
function.
This list of indicator parameters also includes
the TOC value (total organic carbon), which
has not been assigned a limiting value or
criterion but can be considered as a
cautionary warning for action under unusual
circumstances. Another indicator parameter
included in the list is oxidizability. This is a
measure for the sum of all chemically
oxidizable organically bound compounds
present in water.
With reference to drinking water limiting
values, this parameter is no cause for direct
health concern but can lead to regermination
or undesirable disinfection byproducts.
Oxidizability is proportional to the sum of
organically
bound
carbons
that
are
determined as DOC (dissolved organic
carbon) or TOC. Oxidizability can therefore
be replaced by the TOC parameter. The
frequency of determination of the parameter
indicators depends on the volume of water
that is produced or released in a water supply
area.
■ TOC determination in drinking water
When examining carbon compounds in
drinking water, it is apparent that the amount
of inorganic carbons, such as carbonates and
hydrogen carbonates, is much higher than
the organic fraction.
SCA-130-101
Example:
TC = 100 mg/l (RSD = 2%) ± 2 mg/l
(98 – 102 mg/l)
IC = 98 mg/l (RSD = 2%) ± 1,96 mg/l
(96,04 – 99,96mg/l)
Based on error propagation the total error is ±
3,96 mg/l
TOC (calc.) = 2 mg/l ± 3,96mg/l
(- 1,96 - 5,96 mg/l)
The total error is bigger than the TOC-result,
negative results are possible.
According to European Standardization EN
1484 (instructions for the determination of
total organic carbon and dissolved organic
carbon), the difference method can only be
applied when the TIC value (total inorganic
carbon) is smaller than the TOC value.
For drinking water analysis the NPOC
method (non purgeable organic carbon) is
therefore used. The drinking water sample is
first acidified to a pH value of 2. This way the
carbonates and hydrogen carbonates are
transformed into carbon dioxide. The CO2 is
then removed via sparging with carrier gas.
The amount of volatile and therefore
purgeable organic carbon can be disregarded
in drinking water. What remains is a solution
of non-volatile organic carbon compounds.
These can be oxidized to CO2 and detected
via NDIR.
■ TOC-L Series
The sample preparation for the NPOC
method (acidification and sparging) is automatically done in the TOC-L analyzer. The
removing of the TIC can be performed either
in the syringe of the ISP-Module or in the
autosampler with the external spare kit.
The ISP (integrated sample preparation)
module consists of an 8-port valve and a
syringe with sparging gas connection. In
addition to acidification and sparging in the
syringe, the ISP also enables automatic
dilution. This feature facilitates an extended
measuring
range,
dilution
of
highly
contaminated samples and the preparation of
a series of calibration samples from a stock
solution. The ISP module can therefore
considerably reduce time-consuming sample
handling steps.
■ Example of drinking water analysis:
NPOC-Method
Acidification: 1,5%
Sparge time: 5 minutes
10
9
Signal[mV]
The organic fraction is only 1% of the total
carbons. A TOC determination via the
difference method (TOC = TC - IC) will not be
appropriate in this case, as the calculated
TOC value is prone to large statistical errors.
6
3
0
-1
0
7
14
Zeit[min]
■ Recommended analyzer / Configuration
TOC-L CPH
ASI-L (40ml), External Sparge-Kit.
TOC-VWP with ASI-V (40ml)
Sum parameter Total Organic Carbon
TOC – Determination in wastewater
SCA-130-102
Wastewater is water that has been
contaminated by use. In terms of its
composition, wastewater is not homogeneous
but as diverse as its possible sources.
Sewage also includes the liquids that are
discharged and collected from waste
treatment and storage plants”.
This diversity of wastewaters should also be
taken into account during the analysis.
Wastewater can thus contain small amounts
of organic pollutants with little matrix, as well
as highly saline products with high amounts
of organic components.
According to the German Water Resources
Act
(Wasserhaushaltsgesetz,
WHG)
wastewater is defined as follows:
■ Example of wastewater measurement
Below, a strongly saline wastewater from the
chemical industry was analyzed. In addition
to various substances present in low
amounts, the wastewater mainly contained
high amounts of phenolic substances
originating from production processes.
“Wastewater is
1) water whose properties have been
changed by domestic, commercial,
agricultural or other use and the water
(sewage) discharged with it during dry
weather conditions as well as
2) the run-off and collected water (rainwater)
from built-up or paved areas following
precipitation.
Fig. Result of the wastewater
SCA-130-102
A TOC-LCPN was used for the analysis. To
ensure efficient use of the instrument for
large sample quantities, the fully automated
dilution function and the additional high-salt
sample kit were applied. With a dedicated
function, samples could be diluted up to a
factor of 1:50. For the phenol-containing
wastewater, the sample was diluted by a
factor of 1:10. The high-salt sample kit
increases the lifetime of the catalyst for high
salt loads.
In many cases, wastewater contains
particles. Where the wastewaters are not
filtered, the particles need to be held in
suspension by stirring. In order to prevent in
homogeneity
of
the
particles
by
sedimentation within the syringe body,
multiple injections from the same syringe may
not be carried out in this case.
■ Recommended Analyzer / Configuration
TOC-L CPN with normal sensitive Catalyst or
kit for high salt samples (B-Type-Scrubber)
ASI-L (40ml) with stirrer option (for samples
with particles) and External Sparge-Kit
Fig. Combustion tube (of salt kit)
after the long term test
To test long-term stability, more than 300
injections of the saline wastewater were
compared.
The
graph
shows
the
stability
of
measurement of over 300 injections with a
standard deviation of 1.7%. Mean value was
3042 mg/L.
■ Useful instrument parameters::
 Use of integrated dilution function for
automated sample dilution
 In the presence of particles: deactivation
of multiple injection via the syringe.
Sum parameter Total Organic Carbon
TOC –Determination in surface and
groundwater
SCA-130-103
The
German
Water
Resources
Act
(Wasserhaushaltsgesetz, WHG) serves the
purpose of “sustainable water management
to protect waters as a component of the
ecological balance, as a basis of human
existence, as a habitat for animals and plants
as well as a usable good”. The various water
types are defined in this act.
exhibit high levels of TOC concentrations
caused by natural substances or dissolved
harmful substances from the environment.
Surface water
Typical TOCConcentrations in
mg/l
Clean spring water
1-2
Weakly polluted rivers
and streams
2–5
Nutrient-rich stagnant
lakes
5 - 10
Polluted waters
50 - >100
Clean groundwater
(well water)
1 -2
Typical TOC-Concentrations (1)
■ Definitions according to WHG Groundwater is defined as “water that is
below the surface of the ground in the
saturation zone and in direct contact with the
ground or subsoil”. Surface water is
“permanently or temporarily confined flowing
or standing waters, and unconfined waters
from natural springs”. Surface waters include
bodies of water above ground such as lakes,
rivers and streams as well as coastal waters.
Rainwater that has not yet flowed away is
also included.
Surface waters are often contaminated with
particles and harmful substances. They can
only be used as drinking water after
undergoing a treatment process (Wikipedia).
By definition, these waters can be very
different due to regional conditions. They can
Depending on the region, high TIC
concentration (> 100 mg/L) can also occur in
surface water as well as in groundwater.
At TOC concentrations of far below 10 mg/L,
it needs to be ensured that inorganic carbon
is being purged from the solution.
SCA-130-103
The excellent particle tolerance of the
analyzers enables analysis of particlecontaining surface waters. Using the
automatic dilution function, multi-point
calibrations can be generated from a single
standard. In the investigation of unknown
surface waters or groundwater, one of the
samples may exceed the calibration range. In
this case, the TOC Control-L software offers
an option for automatic dilution to bring the
sample back within the calibration range.
■ Example: River water
20
14
Signal[mV]
■ TOC-L
To prepare the sample accordingly, the ISP
module of the TOC-L automatically acidifies
the sample and strips the CO2 originating
from the TIC.
7
0
-2
0
5
NPOC-Method
Acidification: 1,5%
Sparge-time: 5 Minutes
TOC-Concentration: 3,4 mg/l
RSD (3 Injections): 1,4%
■ Recommended analyzer / Configuration
- TOC-LCPH
- ASI-L (40ml) with stirrer option
- External Sparge-Kit
(1) Source: Wikipedia Sum parameter – Total Organic Carbon
TOC – Determination in seawater
SCA-130-104
TOC is an important indicator of the degree of
organic contamination. TOC determination is
used extensively to detect and study
environmental and seawater pollution. In
recent years, increased attention is being
paid to the measurement of the nitrogen
compounds (TN = Total Nitrogen) responsible
for eutrophication.
■ Seawater samples
Seawater has an average salinity of 3.5%
mass fraction. The total salinity fluctuates
depending on each ocean. The Baltic Sea
has a salinity of 0.2 to 2%. Some inland seas
without outlets have far higher water
salinities. The Dead Sea is known for its
salinity of 28%. Chloride ions constitute the
main component of the anions, followed by
sulfate ions. Sodium ions dominate among
the cations, which is why the major proportion
of crystallized sea salts consists of sodium
chloride (common salt). Magnesium, calcium
and potassium ions are represented in
smaller amounts.
■ Are high salt loads a problem?
During thermal catalytic combustion of the
test sample, the dissolved salts crystallize.
Depending on the salt concentration, this can
affect or clog the system.
Maintenance
measures (for instance exchanging the
catalyst) would then be required in order to
render the instrument operational again. Of
course, it is desirable to keep the
maintenance intervals as long as possible.
■ TOC-L Series
The TOC-L series offers various possibilities
to keep the maintenance need for highly
polluted samples as low as possible. The
analyzers are operated under catalytic
combustion at 680 °C. This temperature is
lower than the melting point of sodium
chloride and therefore prevents deactivation
of the active centers of the catalyst by a melt.
The use of the platinum catalyst ensures
complete conversion of organic carbon
compounds to CO2.
The highly sensitive NDIR detector allows
small injection volumes (typically 20 - 50 µL)
that reduce absolute sample input onto the
catalyst.
SCA-130-104
■ Kit for high-salt samples
The TOC-L series features a kit for high-salt
samples, which significantly increases
instrument availability.
Using this kit in a seawater application, it was
possible to carry out 2500 injections without
maintenance (injection volume of 40 µL).
The kit consists of a combustion tube with a
special geometry and a unique catalyst
mixture.
Compound
Melting point
NaCl
801°C
KCl
773°C
Na2SO4
888°C
MgCl2
708°C
CaCl2
782°C
K2SO4
1.069°C
Tab. Melting point of different salts
■ Simultaneous TN determination using
the TNM-L
Based on the similar oxidation process, the
TNb determination can be carried out
simultaneously with the TOC measurement.
For this application, the TNM-L option is
installed on the main TOC-L system.
In this application, sample acidification is
carried out with sulfuric acid which is used to
modify the sample matrix. While NaCl has a
melting point of 801 °C, the melting point of
NaSO4 is higher (888 °C). The potassium
salts of sulfuric acid also have a significantly
higher melting point than those of
hydrochloric acid. This has a positive effect
on the lifetime of the combustion tube.
Figure: Simultaneous TOC/TN-Determination
■ Recommended analyzer / Configuration
TOC-L CPN
ASI-L (40ml), External Sparge-Kit.
Kit for high-salt samples
TNM-L
Sum parameter – Total Organic Carbon
TOC determination in solid samples
using the suspension method
SCA-130-105
The TOC content in solids plays an important
role in the classification of soils, sludges and
sediments. According to the German
Ordinance on Environmentally Compatible
Storage of Waste from Human Settlements
(Abfallablagerungsverordnung,
AbfAblV),
TOC in solid materials is one of the key
parameters for the characterization of wastes
as part of the acceptance control of landfills.
This important control measure requires a
fast and simple TOC determination method
and, at the same time, a robust and
statistically reliable method that is based on
the inhomogeneous composition of soils.
■ Suspension method Several years ago, Shimadzu developed the
so-called suspension method in cooperation
with responsible authorities and the Albo-tec
environmental
laboratory
in
Bochum,
Germany. In this method, the solid sample is
processed in a specific way so that it can
subsequently be treated as a liquid, particlecontaining sample. This method was
successfully applied in several round robin
tests and has, since June 2009, also been
described in the draft DIN EN 159536. This
new standard is intended to replace DIN EN
13137 and describes the established solid
sample combustion method as well as the
novel suspension method (see annex).
■ Analytical process
To date, the established regulations describe
a method whereby a weighed solid sample is
combusted in a stream of air or oxygen. The
CO2 generated during combustion is
subsequently detected and quantified using a
calibration curve. The inhomogeneity of the
soils has a direct effect on the distribution of
the measuring data – each weighed solid
sample can only be combusted once.
Approximately 200 mg of the dried and
ground sample is weighed into an Erlenmeyer
flask. The sample is subsequently suspended
in a diluted hydrochloric acid solution. The
acidic solution serves to break down the
carbonates present in the sample and, at the
same time, form the suspension medium.
SCA-130-105
The suspension is homogenized for several
minutes at a speed of 17,000 – 18,000 rpm
using a dispersion unit. It is critically
important to select a suitable precision tool.
After homogenization, the suspension is
transferred directly to autosampler vials.
Critical for subsequent measurement is the
use of a magnetic stirrer in the autosampler
to ensure that the suspension remains
homogeneous during sampling. After all, the
small particles should not sediment, but
remain uniformly distributed throughout the
solution. The suspensions can now be
repeatedly injected and analyzed.
■ Example of suspension determination
NPOC-Method (Acidification is done by
creation of the suspension)
Sparge-time: 5 Minutes
Injection volume: 90µl
Multi-Injection is deactivated
■ Statistic
This method enables not only automated
solid sample analysis using an autosampler,
but also parallel measurement of solid and
liquid samples in the same sample table and
the same sample tray. In addition to speed,
this method is also impressive in terms of
robustness. The possibility of multiple
injections enables differentiation of small
variations due to weighing and measuring.
Peak-No
Areas
1
2
3
4
5
6
7
8
9
10
MW
RSD in%
183,7
180,9
189,0
183,8
179,9
179,9
179,9
186,9
181,6
177,6
182,2
1,88
Result of
suspension
TOC in mg/l
24,71
24,23
25,61
24,72
24,06
24,06
23,89
25,25
24,35
23,67
24,5
2,52
Result of
Sample TOC
in %
2,47
2,42
2,56
2,47
2,41
2,41
2,39
2,53
2,37
2,37
2,45
2,49
■Recommended analyzer / Configuration
TOC-L CPN
ASI-L (40ml) with stirrer option and
external Sparge-Kit.
Sum parameter – Total Organic Carbon
TOC determination in particle-containing
samples - Cellulose test according to EN 1484 SCA-130-106
Depending on their origin, different effluents
can contain substantial amounts of insoluble
solids. These include clearly visible
components that, in some cases, sediment
very quickly. This applies particularly to heavy
particles such as sand grains. Suspended
solids such as fibers or flakes are naturally
less likely to sediment. However, they also
cause a certain inhomogeneity of the sample
matrix.
A variant of TOC determination is the
detection of DOC, Dissolved Organic Carbon.
The wastewater sample is filtered through a
membrane filter with a 0.45 µm pore size and
subsequently measured. In contrast to DOC,
TOC (Total Organic Carbon) determinations
must detect the total organic carbon in a
sample, including the insoluble components.
According to DIN 1484, the suitability of a
TOC measurement system for the analysis of
wastewater samples that contain solid matter
must be tested. This is carried out using the
so-called cellulose test (Appendix C of the
above-mentioned standard).
■ Cellulose test according to DIN EN 1484
The cellulose test is based on an aqueous
cellulose suspension with a carbon content of
100 mg/L. This corresponds to 225 mg
cellulose. The particle size ranges from 20
µm to 100 µm. Homogenization may only be
carried out under stirring. Alternative methods
such as ultrasound can break up the particles
and thereby provide erroneous results. Large
particles in particular have a tendency
tosediment rapidly.
Stirring speed is critical for this reason. Very
slow stirring leads to increased particle
sedimentation. Extremely high stirring speeds
lead to inhomogeneous particle distribution
due to centrifugal force. DIN 38402 part 30,
dealing with sample homogenization, serves
in this context as an excellent reference. A
solution should be stirred in such a way that
the vortex will amount to 10% of the filling
level.
For three consecutive injections, the mean
value must lie within the range of 90 mg C/L
to 110 mg C/L (corresponding to a recovery
of 90 – 110 %). The relative standard
deviation (RSD) may not exceed 10 %.
SCA-130-106
■ Particle tolerance of the TOC-L series
This test was carried out using a TOC-L
system (TOC-LCPH including ASI autosampler
with integrated stirring option).
■ Settings
 Injection volume 90 µL
 TC measurement for the particle test
 NPOC measurement in the autosampler
 Stirrer in the ASI-L,
 medium stirring speed
 No multiple injection
Used Cellulose-Standard:
Cellulose powder MN 100
Particle size: 20-100µm
Supplier: Machery-Nagel
■ System Configuration
- TOC-L CPX
- ASI-L (40ml recommended) with particle
needle l
- Stirrer option
- Offline-Port can be used too
■ Results
The cellulose suspension was injected five
times according to the above settings.
NPOC = 98,4 ± 2,2 mg/l (RSD = 2,27 %).
This corresponds to a recovery of 98,4 %.
.
The TOC-LCPH was first calibrated using the
automated dilution function in the range of 10
– 100 mg/L.
Abb.2 Peak graph of cellulose-suspension
These values are clearly within EN DIN
specifications
Figure 1 Calibration curve 10-100mg/L
Sum parameter – Total Organic Carbon
SCA-130-107
Determination of particulate organic
carbon after filtration
(glass fiber suspension) A limnological research laboratory tackled the
problem of determining the particulate TOC
content of the sample independently of DOC
(Dissolved Organic Carbon) content. The
water sample was filtered through filters of
varying pore sizes. Particles of varying sizes
remain on the filter. The question arose, how
particulate TOC can be best measured.
■ The field test
A TOC analyzer with autosampler was used
for the field test. After calibration of the TOC
system, the test solution was measured 10
times. The test solution consisted of a glass
fiber suspension in hydrochloric acid (five
glass fiber filters dispersed in 500 mL) that
was
continuously
stirred
during
measurement. To test the catalyst, a
standard solution with a TOC of 50 mg/L was
injected after each 10th measurement. After
100 injections and visual inspection of the
catalyst and the catalyst tube, the measuring
cycle was somewhat increased. Function of
the catalyst was now checked using the
standard test solution only after every 20
injections of the glass fiber suspension.
Fig. Used glass fiber filter
A possibility would be to shred the filter and
disperse it in water, and to measure the
obtained suspension directly using the TOC
system. This requires use of TOC-free glass
fiber filters. This uncommon question requires
a field test. Based on the melting range of
glass fiber (about 550 °C) it was necessary to
ensure that the glass fiber content would not
clog or deactivate the catalyst (680 °C) and to
establish where the oxidizing power
diminishes.
After a total of 450 injections, no visible
change of the catalyst could be detected. Nor
did the oxidative properties change or
deteriorate in any way. Reproducibility of the
results also did not reveal any change.
SCA-130-107
■ Statistics
As an example, the figure below shows the
final 20 injections of the field test. Relative
standard deviation was 1.8%.
The standard solution after the last glass fiber
suspension injection cycle resulted in a TOC
recovery of 97.6%.
The TOC field test clearly showed that the
oxidative power of the catalyst, even after
several hundred glass fiber suspension
injections, did not deteriorate. Active centers
of the catalyst were not affected, nor did they
fuse.
Injection
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Mean Value
SD
RSD in %
Conc. In mg/l
0,7430
0,6947
0,6819
0,6850
0,6959
0,6930
0,6966
0,6831
0,6901
0,6997
0,6943
0,6890
0,6896
0,6871
0,6945
0,6934
0,6982
0,6936
0,6951
0,6924
0,6945
0,0124
1,78
Tab. Peak areas and statistics
of the last 20 injections
Fig. Peak graphs of the last 20 injections
■ Recommended analyzer / Configuration
TOC-L CPN
ASI-L (40ml) with stirrer option and external
Sparge-Kit.
Shimadzu Deutschland GmbH
Info@shimadzu.de
www.shimadzu.de/home 2. Pharmaceutical industry
Pharmaceutics is an ancient science that
has supported people with remedies to
help alleviate pain and heal illnesses.
After medication, certain substances are
expected to unfold their beneficial effects – while side effects from interfering substances and contaminations are
undesirable. This is why it is important
to use the purest possible substances
and purified equipment and materials in
the production of drugs.
To meet this standard, legislators have
published Pharmacopoeias. These include methods and rules for the manufacture, storage, quality and testing of
drugs. For drug manufacturers, complying with the rules and methods of the
Pharmacopoeia is mandatory.
TOC determination is also described in
the Pharmacopoeia (for instance the
European Pharmacopoeia = EP). The
sum parameter serves as a measure of
contamination by organic compounds.
Not only the method itself is described,
but also a test to verify the suitability
of a TOC analyzer for the analysis.
drug batch, the TOC parameter is used
for the evaluation of the cleaning process. The TOC not only mirrors the presence of drugs, but also reveals other
contaminants such as those from cleaning agents.
In addition to ultrapure water required
for the manufacture of drugs, water for
injections – water that is directly injected into the bloodstream of the human
or animal body – is also tested for its
TOC content. The Pharmacopoeia actually specifies a maximum TOC limit value
for such specific waters.
With its TOC analyzers, Shimadzu offers
systems that are suitable for many different TOC analysis issues in the pharmaceutical industry. In addition to the
lowest detection sensitivity, the robust
analyzers offer the highest precision and
accuracy. Just like the analyzers themselves, the operation and evaluation
software complies with all requirements
of the FDA and the Pharmacopoeia.
Many drugs are manufactured in batch
mode operation. Prior to the production
of the next batch, materials and working equipment must be extensively
cleaned. In order to verify that the
equipment is free from the ‘previous’
Further information can be found in the
individual application notes (for instance ‘TOC determination in ultrapure
water, cleaning validation or in accor-
dance with EP 2.2.44’). In addition to
pharmaceutical applications, there are
also application notes and information
on ‘Environmental analysis’, ‘Chemical
industry’, ‘TOC special applications’,
‘TOC in daily practice’ and ‘TOC process
analysis.’
Sum parameter – Total Organic Carbon
SCA-130-201
TOC determination in ultrapure water –
Comparison of the various oxidation
techniques
Ultrapure water is one of the most widely
used excipients in the production of
pharmaceuticals. It is also used for cleaning
purposes. Different application areas require
different grades of ultrapure water quality.
These grades are defined in the European
Pharmacopoeia, which distinguishes between
‘Purified Water’, ‘Highly Purified Water’ and
‘Water for Injection’ (‘The United States
Pharmacopoeia, however, does not use the
same classification as the European
Pharmacopoeia’).
Water Purified is used in the manufacture of
pharmaceuticals that do not require any other
standard. The organic content is determined
either via the TOC value (0.5 mg/L) or via the
permanganate test (purified water in bulk).
■ TOC determination in ultrapure water
Two oxidation techniques are now commonly
used in TOC analysis:
1. Catalytic combustion, where carbon
compounds are converted into CO2 using a
catalyst under high temperatures with
subsequent detection of the resulting CO2
using an NDIR detector.
2. Wet chemical oxidation, which uses a
combination of UV irradiation and persulfate
for oxidation. Both methods can be applied
for the determination of ultrapure water.
Water for injection is used for the
preparation of injection solutions and is
produced by distillation. The TOC content
may not exceed 0.5 mg/L (water for injection
in bulk).
Water Highly Purified is a sterile ultrapure
water for the manufacture of pharmaceuticals
that do not require a ‘Water for Injection'
standard. It is also often used for the final
rinse during cleaning and is usually produced
by reversed osmosis. The TOC content may
not exceed 0.5 mg/L.
.
■ TOC-LCPH: Oxidation via catalytic
combustion
The TOC-L CPH uses the proven catalytic
oxidation at 680 °C.
SCA-130-201
The integrated ISP sample preparation unit
(an 8-position switching valve with syringe
and sparging gas connection) considerably
reduces the users’ workload, as the
instrument carries out dilution, acidification
and sparging fully automatically.
detection limit (0.5µg/L) and excellent
reproducibility in the lower ppb range. The
TOC-VWP/WS is therefore highly suitable for
TOC determination in the ultra-trace range.
TOC-V WP Sample measurement
Method:
NPOC (3% Acid, 3 min sparge)
Persulfatsol.: 1,5mL
Injection vol.: 20,4 mL
Result: 2,44 ± 0,42 µg/L TOC (NPOC)
Fig. NPOC- Calibration (Blank and 500µg/L)
When using the high sensitivity catalyst, the
detection limit is approximately 4µg/L. In
addition, the combustion technique can be
used in combination with the TNM-L module,
whereby a single injection is sufficient for
simultaneous determination of the total bound
nitrogen.
Simultaneous
TOC/TNb
determination is highly suitable for cleaning
validation, as this enables differential
determination between cleaning agent and
product.
■ TOC-VWP/WS: Wet chemical oxidation
The key technique of the TOC-VWP/WS
analyzer is the powerful oxidation via the
combination of sodium persulfate and UV
oxidation at 80 °C. The TOC-VWP/WS features
an automatic reagent preparation function
that eliminates possible contamination of the
persulfate solution. This ensures that the
TOC value truly originates from the sample –
and not from the reagent solution used. The
large injection volume (up to 20.4 mL) in
combination with the highly sensitive NDIR
detector, leads to an extremely low
Abb. Peak graphik of TOC-VWP measurement
■ Conclusions
Both types of instruments with their different
oxidation methods can be used for TOC
determination according to the European
Pharmacopoeia. The advantage of the
combustion method is its high oxidation
potential, particularly for samples containing
particulate matter. Moreover, simultaneous
TOC/TNb measurements can be carried out,
leading to a higher information content of the
analysis. The advantage of wet-chemical
oxidation is its high injection volume, which
leads to higher sensitivity and therefore
enables high precision measurements in the
lower ppb range.
■ Recommended analyzer / Configuration
TOC-L CPH with high sensitivity catalyst
ASI-L (40ml), External Sparge-Kit.
TOC-VWP with ASI-V (40ml)
Sum parameter – Total Organic Carbon
TOC determination in cleaning validation
– final rinse
SCA-130-202
The highest purity and most careful handling
of substances and active ingredients is an
important requirement in the manufacture of
pharmaceuticals. An effective removal of
production residues in pharmaceutical plants
is an essential precondition. A well-cleaned
pharmaceutical production system prevents
contamination
and,
consequently,
the
adulteration of the produced drug. This is
particularly important in the production of
active ingredients in batch processes, as the
system is used for different products and
contamination of the next product must be
prevented.
Because time and temperature, as well as the
use of cleaning agents and solvents are
optimized, CIP cleaning is highly effective.
Moreover, automatic cleaning allows a
standardized and, therefore, an easily
validated procedure.
■ Sampling and analysis
In case of CIP cleaning, the rinsing liquid of
the final rinse solution is sampled and
analyzed. This is a very simple, easily
automatable and fast method. When water is
used as a solvent, TOC analysis is suitable
for subsequent analysis.
■ TOC-Analysis
TOC analysis is applied for the determination
of the total organic carbon content as a sum
parameter. The carbon content of the sample
is oxidized to CO2 and detected by an NDIR
detector. Analysis of final rinse samples is,
therefore, fast and simple (analysis time:
approx. 4 min). The determined TOC value
reflects any contamination by starting
materials, products, byproducts or cleaning
agents, as long as they contain carbon.
■ Cleaning methods: Clean in Place
CIP cleaning (clean in place) is performed
automatically and without disassembly of the
production system. The production system
must, therefore, have a CIP design. This
includes the use of rinsing heads, no dead
volumes, collection tank and recycling
possibilities
for
the
detergents.
■ Shimadzu TOC Series
With its TOC-L series, Shimadzu offers a
highly suitable tool for cleaning validation.
The modular design simplifies the analysis –
no matter whether one wants to measure final
rinse samples or swab samples.
SCA-130-202
For users who prefer wet-chemical oxidation
for the determination of TOC, the TOC-VWP
analyzer with its various options, is available.
The key technique of the TOC-VWP analyzer
is the powerful oxidation via the combination
of sodium persulfate and UV oxidation at
80°C.
The TOC-LCPH employs the proven catalytic
oxidation at 680 °C. The integrated sample
preparation (ISP) module greatly reduces the
users’
workload,
as
the
instrument
automatically carries out the dilution,
acidification and degassing steps.
Practical Example:
■ Instrument / Measurement parameter
Unit:
TOC-LCPH
Catalyst:
High sensitivity catalyst
Meas.-typ:
NPOC
Cal-Curve:
2-Punkt Calibration Curve
0-3 mgC/L (KHP)
Injection vol.: 500 μL
■ Results
Compound
Blank
Tranexamic acid
Anhydrous caffeine
Isopropylantipyrine
Nifedipine
Gentashin ointment
Rinderon ointment
TOCResult
0,030mg/L
2,14mg/L
2,19mg/L
2,20mg/L
2,17mg/L
0,117mg/L
0,333mg/L
Recovery
105 %
108 %
109 %
107 %
4,35 %
15,2 %
From the results, it can be concluded that the
final rinse method only shows good
recoveries for water-soluble compounds.
(Further information is available in the
application note Japan TOC O41)
Fig. ISP-Module of TOC-L series
The possibility for simultaneous determination
of the TNb (total nitrogen) using the TNM-L
module
enables,
if
necessary,
a
differentiation between cleaning agent and
product. This may be of great importance,
particularly for biopharmaceutical products.
Sum parameter – Total Organic Carbon
TOC –Determination in cleaning
validation - swab method
SCA-130-203
Cleaning
validation
substantiates
the
effectiveness of a cleaning process and
ensures that no residues remain on the
surfaces of the production equipment. For the
detection of contaminations, validated
analytical methods must be used that are
sensitive enough to determine the defined
acceptable residue level. In general, residue
limits of 10 ppm or 1/1000 of the usual
therapeutic dose of an active substance are
used as acceptance criteria.
■ Sampling and analysis
In COP cleaning, the wiping method (swab) is
used for sampling of visible residues. These
include coatings, crusts, material deposited in
corners and edges, and especially poorly
soluble substances. The swab can be
extracted in a solvent and the extracted
solution is subsequently analyzed. If water is
used for extraction, TOC analysis is suitable
for subsequent analysis. Alternatively, the
swab can also be measured directly (using a
carbon-free swab) using a TOC solid-sample
module.
■ Measuring system for the swab test
The modular design of Shimadzu’s TOC-L
series
now
enables
the
additional
determination of the swabs using the same
instrument. For this purpose, a solid-sample
module (SSM-5000A) was connected to the
main instrument, either a TOC-L series
combustion system or the wet-chemical
model of the TOC-V series.
■ Cleaning methods: Clean out of Place
For COP cleaning, the entire production
system must be disassembled and the
components must be cleaned individually.
This procedure is very time consuming and
labor intensive. Due to the individual
cleaning,
this
procedure
cannot
be
standardized. Advantages are, however, the
low investment costs of the system and the
possibility of visual inspection.
For TC determination, the swab is placed in a
ceramic boat and transferred into the oven,
which is heated to 900 °C.
SCA-130-203
There, all carbon compounds are oxidized to
CO2. To ensure complete oxidation, there is
an additional catalyst in the combustion tube.
The resulting CO2 is then transported to the
detector in the main instrument. The NDIR
detector of the TOC-L series contains a
tandem cell that consists of a long cell (200
mm) and a short cell (1 mm). By default, the
long cell is used for water analysis and the
short cell for solid-sample analysis. To attain
a higher sensitivity for the analysis of solids,
the solid-sample module can also be
connected to the long, and thus the more
sensitive, measuring cell. This can be
realized using an upstream switching valve.
This way, the system can now readily be
used for cleaning validation without any loss
in flexibility of switching between water and
solid-sample analysis.
■ Preparation
As the TOC analysis involves a sum
parameter, it is important to ensure that the
measured carbon really originates from the
sampled surface. Some preparation is,
therefore, important.
First, the swabs used must be carbon-free.
This is why fiber optics swabs are used,
which are annealed at 600 °C and are stored
under dry conditions using an inert gas. The
same pretreatment is required for the ceramic
boat. All tools used, such as tweezers and
glass containers must be free from carbon.
■ Swab test
For the wiping test, two pretreated swabs are
sampled, the lower swab is moistened with
water and the defined surface is wiped
according to the prescribed procedure. The
used swab is now folded, placed in the clean
ceramic boat and transferred to the TOC
measuring system.
Depending on the expected concentration or
defined limit value, the system configuration
and calibration curve is selected. The
calculated amount of carbon is now
correlates directly to the area of the wiped
surface.
Practical example:
■ Instrument/ Measurement parameter
Unit:
TOC-LCPH + SSM-5000A
(shortcut of IC-flow line)
Detector cell: Short Cell
Carrier gas: 400 mL/min oxygen (SSM)
Meas.-typ:
TC
Cal-Curve:
1-Point Calibration curve wiht
30μL of 1%C Glucose solution
Swab:
Advantec QR-100 quartz glass
Filter paper (45 mm)
Prepared at 600°C,15min
■ Result
Blank
Tranexamic acid
TOCResult
0,00
202 µgC
101 %
Anhydrous caffeine
Isopropylantipyrine
Nifedipine
Gentashin ointment
Rinderon ointment
201 µgC
210 µgC
212 µgC
200 µgC
209 µgC
100 %
105 %
106 %
100 %
104 %
Compound
Recovery
(Further information is available in the
application note Japan TOC O41)
Sum parameter – Total Organic Carbon
TOC-Determination according to
EP 2.2.44
SCA-130-204
Since
the
USP
(United
States
Pharmacopoeia)
regulations
for
the
determination of Aqua Purificata and Aqua ad
injectabilia has been implemented into the
European
Pharmacopoeia
(EP),
TOC
analysis has become increasingly established
in quality control. Users who test the TOC
content in pharmaceutical water must
regularly test their TOC system using a
system suitability test according to the
method described in the EP 2.2.44
guidelines.
■ System suitability test
For the system suitability test, a standard
sucrose solution with a carbon content of 0.5
mg/L is prepared. A control solution of 1,4benzoquinone with the same carbon content
was subsequently prepared. The blank water
(ultra-pure water) used for this purpose may
not exceed a TOC content of 0.1 mg/L. For
the system suitability test, all solutions
including the blank water are subsequently
measured and the resulting signals are
recorded.
Blank water: rw
Standard solution (sucrose): rs
Control solution (benzoquinone): rss
The peak area of the blank water is
subtracted from the peak areas of both
standard solutions. The recovery of the
benzoquinone standard is then calculated
with respect to the sucrose standard.
■ European Pharmacopeia
The EP 2.2.44 guidelines do not prescribe
any particular oxidation technique for TOC
determination. The TOC systems, however,
must be able to differentiate between
inorganic and organic carbon. This can be
carried out either via removal of the inorganic
carbon (NPOC method), or via a separate
determination (difference
method). The limit of detection for TOC
should be at least 0.05 mg /L. The
applicability of the method must be
determined via a system suitability test.
Recovery in %:
rss  rw
 100
rs  rw
Results between 85 - 115% are acceptable.
The ultrapure water sample corresponds to
the guidelines when its response signal (ru)
does not exceed rs - rw.
SCA-130-204
■ TOC-Control L software
The TOC-Control L software simplifies the
implementation of the system suitability tests
using integrated templates for the creation of
calibration curves and the measurement of
the control sample.
The determination of benzoquinone is set in
the sample / method properties wizard.
Fig. Calibration curve wizard
The following figure shows an example of an
EP calibration curve (2 points, blank and 500
µg/L).
Fig. Benzochinone-Determination
After measuring the benzoquinone sample,
the software automatically calculates the
recovery according to EP 2.2.44, whereby the
peak area values for the blank sample and
the sucrose sample are obtained from the
calibration curve. The result is listed under
the column ‘Notes’ in the sample table
(Figure below).
Fig. Calibration Curve
Fig. Result of system suitability test in sample table
3. Chemical industry
The most commonly used compound in
the chemical industry is water – not
only as a solvent in processing, but also
as an energy carrier in the cooling or
heating cycle. As vast amounts of water
are needed, chemical industries are
often located close to large bodies of
flowing water. Water used as processing
water or as cooling water is cleaned and
subsequently led back to the river or
stream. For environmental protection,
these waters are subject to specific control and monitoring measures. As the
TOC non-specifically detects all organic
compounds, this parameter has also
proven to be invaluable here.
Large chemical industrial parks have
their own wastewater treatment plants
for cleaning wastewaters emanating
from the various chemical plants. In
order to evenly distribute the wastewater charges over the participating
companies, the TOC load of the individual wastewaters is often used as a basis
for calculation. Companies delivering
higher TOC loads are required to pay
higher charges.
Incoming goods control is important in
the chemical industry. Impurities present
in reagents often also constitute the
impurities in products. In addition to the
targeted analysis of known compounds,
sum parameters can help to assess the
raw chemicals in terms of their impurities. The TOC plays an important role
here: this parameter describes the contamination through organic compounds
and specifies the total amount of organic carbon. TOC can, therefore, also be
used for the assessment of inorganic
chemicals.
The great challenge for TOC measurements in chemical products is to devel-
op protective mechanisms to help protect instruments and their components,
as well as to prevent damage by, for
instance, acid fumes or high salt loads.
For this purpose, Shimadzu’s TOC-L
series offers several gas washers and
options to ensure safe and problem-free
analyses.
A further challenge is to attain a stable
and reproducible oxidation to ensure
that no fluctuating or strongly tailing
peaks are recorded. In addition, the
measuring values should remain stable
over a longer measuring interval.
In order to cover this wide range of analytical tasks in the chemical industry,
flexible systems are needed that are
easily adapted to the task in question
via various options, kits and modules.
Shimadzu offers TOC systems that are
highly suitable for such analytical prob-
lems. Because of their modular design,
the instruments in the TOC-L series can
be equipped for any possible measurement task.
The individual application notes (for
instance ‘TOC determination in hydrochloric acid, brines or sodium hydroxide’) contain further information. In addition to applications in the chemical
industry, application notes are also
available on ‘Pharmaceutical industry’,
‘Environmental analysis’, ‘TOC special
applications’, ‘TOC in daily practice’ and
‘TOC process analysis.’
Sum parameter – Total Organic Carbon
TOC – Determination in hydrochloric acid
SCA-130-301
Acids, in particular concentrated hydrochloric
acid, represent a large group of inorganic
chemicals frequently used in the chemical
industry. TOC determination in concentrated
hydrochloric acid poses an enormous
challenge to the analyzers that are used for
this purpose.
In general, it is possible to greatly dilute the
substance to be analyzed in order to
eliminate matrix interferences. But sometimes
it is necessary to achieve very low limits of
detection (with reference to 37% hydrochloric
acid) of 1 mg/L.
■ TOC Measuring Method The 37% hydrochloric acid solution was
manually diluted to a ratio of 1:2 with water in
order to obtain an 18.5% hydrochloric acid
solution.
TOC-L CPH with OCT-L
■ Acid challenge The great challenge is to develop protective
mechanisms to help protect instruments and
their components, as well as to prevent
damage by acidic fumes. For this purpose,
the TOC-L series offers several gas washers
that bind and eliminate the chlorine gas
formed in the flow line of the system in
various ways.
Another challenge is to attain a stable and
reproducible oxidation process to ensure that
no fluctuating or tailing peaks are being
recorded. In addition, the measuring values
should remain stable over a longer measuring
interval.
Abb.2 Mehrpunktkalibration mit
Verdünnungsfunktion
Calibration was carried out in the range of 0.5
to 10 ppm. The automatic dilution function of
the analyzer automatically executes this
calibration from a single stock solution. The
injection volume was 150 µL. In case the
TOC contamination of the hydrochloric acid
exceeds the measuring range of the
calibration, the automatic dilution function of
the analyzer will readjust the hydrochloric
acid solution to fit the measuring range.
■ Verification the measuring method
After calibration, the TOC content of the
concentrated hydrochloric acid solution was
determined.
SCA-130-301
To investigate matrix influences, a potassium
hydrogen
phthalate
solution
was
subsequently
added
to
the
18.5%
hydrochloric acid solution to increase the
TOC by 5 ppm (Figure 3 and Table 1).
The relative standard deviation
measurements was 3.4%. The
graph shows the progression of
values of the hydrochloric acid
over all
following
the TOC
injections.
Fig.4: Result of longterm stability
Fig.3: Results of original and spiked hydrochloric
solution
Blank values and standards (10 ppm) were
alternately measured between the individual
measurements.
Figure 3 and Table 1 show the results of the
individual measurements of the hydrochloric
acid as well as the measurements of the
spiked hydrochloric acid.
TOC result of 18,5% hydrochloric acid in mg/l
Injection
Original
Spiked with
5ppm TOC
1
4,901
10,46
2
4,858
10,24
3
4,91
10,39
4
4,716
10,64
5
4,728
10,28
6
4,739
10,35
7
4,966
10,34
8
4,71
10,36
9
4,662
10,42
10
4,733
10,33
11
4,659
10,11
12
4,625
10,27
13
4,552
10,06
Mean value
4,75
10,33
SD
0,12
0,15
RSD in %
2,6
1,4
Tab. 1: Values of each injection
■ Long-term stability
To investigate the long-term stability of the
method, the 37% hydrochloric acid solution
was again diluted to a ratio of 1:2 with water
and injected 76 times (150 µL).
Fig. 5: Sequence of hydrochloric acid, blank (pure
water) and Standards (10 mg/l)
■ Recommended analyzer / configuration
 TOC-LCPH with a normal sensitive catalyst
(without glass wool at the bottom of the
catalyst tube)
 B-Type scrubber with SnCl2 solution
 Copper bead scrubber with pH paper
 Bypassing the blank check vessel
 Substituting water for phosphoric acid (IC
vessel)
 OCT-L 8-port sampler
Sum parameter – Total Organic Carbon TOC – Determination in nitric acid
SCA-130-302
Organic contaminants present in basic
chemicals may constitute the impurities in
products. This is why quality control of the
reactants is indispensable.
Calibration of the TOC-L system was carried
out using the automatic dilution function in the
range of 0.5 mg/L to 10 mg/L.
Fig. Multi-point calibration
with dilution function
The determination of organic contaminations
in concentrated nitric acid (69%) becomes a
challenge when the required detection limit
does not allow large dilution steps.
An example is the TOC determination in a
69% HNO3 solution with a detection limit of <
10 mg/L.
■ Sample preparation
For sample preparation, the 69% HNO3
solution was diluted to a ratio of 1:10 with
ultrapure water.
Compound
(concenDilution
Conz. [%]
tration)
1 : 10 diluted with
Nitric Acid
water
Ca. 7%
(69%)
(5ml / 50ml)
To protect the NDIR detector, the B-type
scrubber was used together with the halogen
scrubber.
■ Matrix interferences
In addition to CO2, various nitrogen oxides
are formed from the organic components
during the combustion of nitric acid.
Excessively high levels of NO3 can lead to
significant amounts of N2O (nitrous oxide).
Nitrous oxide exhibits absorption bands in the
same IR detection range as CO2 and can,
therefore, be misinterpreted for CO2. In
addition, nitrous oxide can cause tailing and
can affect the peak symmetry.
Due to the high solubility of N2O in water, the
gas is dissolved in the B-type scrubber and
will not reach the detector.
SCA-130-302
■ Result
The duplicate NPOC determination of a nitric
acid produced the following results:
Sample
NPOC
[mg/l]
RSD
[%]
36,9
1,4
33,4
3,0
Nitric Acid
(69%)
Nitric Acid
(69%)
To investigate this matrix influence, an
additional dilution (1:10) of a 69% nitric acid
solution was carried out and a potassium
hydrogen phthalate stock solution was
subsequently added to increase the NPOC
content by 5 ppm. (Note: This corresponds to
an increase to 50 ppm for the 1:10 dilution).
Sample
Nitric Acid (69%)
Nitric Acid (69%)
Spiked with 50 ppm
KHP
NPOC
[mg/l]
25,1
RSD
[%]
1,3
76,2
1,8
The use of suitable gas washers (scrubbers)
enables reproducible TOC measurements in
concentrated nitric acid.
■ Recommended Analyzer / Configuration
TOC-L CPH with normal sensitive Catalyst
B-Type-Scrubber
OCT-L (8-port Sampler)
Sum parameter – Total Organic Carbon
TOC – Determination in sulfuric acid
SCA-130-303
Acids are a group of frequently used
inorganic chemicals used in the chemical
industry. In particular, sulfuric acid is used in
a wide range of applications.
The following SO2 scrubbers are available:

Sulfix (WAKO Chemicals, Fuggerstr. 12,
41468 Neuss, Germany). The Sulfix
scrubber is installed underneath the
normal sensitive catalyst and enables
selective filtration of the formed SO2.

Mist scrubber (cartridge)
Just like the halogen scrubber, the ‘Mist
scrubber’ is used in the flow line for SO2
absorption.
In the experiment described below, the
NPOC content of a 98% sulfuric acid solution
is determined.
Sulfuric acid in a concentration range to
1%.can be directly measured using a TOC-L
analyzer Higher sulfuric acid concentrations
can lead to tailing and, consequently to
increased measurement values because high
sulfate concentrations (> 5000 mg/L) can
lead to the formation of large amounts of SO2
vapors. SO2 exhibits absorption bands in the
same IR detection range as CO2 and can,
therefore, be misinterpreted for CO2.
To determine organic contaminations in
highly concentrated sulfuric acid, additional
SO2 scrubbers are used.
The required purity criterion and the required
limit of detection was < 10 mg/L.
■ Sample preparation
The concentrated sulfuric acid was diluted
with ultrapure water to a ratio of 1:10 to
decrease the concentration as well as the
viscosity of the sulfuric acid.
Compound
(ConcenDilution
Conc.
tration)
Sulfuric
acid (98%)
1 : 10 diluted
with water
(5m/50ml)
Ca. 10%
The dilution has to be carried out with the
utmost care and caution, as the sulfuric acid
reacts violently upon the addition of water
(heat generation).
SCA-130-303
The system is calibrated using the automatic
dilution function in the range of 0.5 mg/L to 10
mg/L.
■Result
The duplicate determination of sulfuric acid
yielded the following results:
Sample
Sulfuric acid
(98%)
Sulfuric acid
(98%)
NPOC
[mg/l]
RSD
[%]
<10 (4,6)
-
<10 (5,4)
-
Fig. Multi-point calibration
with dilution function
The sulfuric acid fulfilled the required purity
criteria of TOC < 10 mg/L.
■ Kit for high-salt samples
For the determination, a TOC-LCPH equipped
with a kit for high salt loads was used. The kit
consists of a special catalyst tube, a special
mixture of various catalyst beads and a
ceramics grid, which replaces the platinum
net.
The use of suitable gas washers (scrubbers)
enables reproducible TOC measurements in
concentrated sulfuric acid.
Sample acidification when using the high-salt
kit, is carried out with sulfuric acid. Sulfuric
acid is used to modify the sample matrix.
While NaCl has a melting point of 801 °C, the
melting point of NaSO4 is higher (881 °C).
This has a positive effect on the lifetime of the
combustion tube.
For this reason, sulfuric acid is measured
directly
using
the
high-salt
kit.
■ Recommended analyzer / Configuration
TOC-L CPH
OCT-L
High-Salt-Kit
B-Type-Scrubber with diluted hydrochloric
acid with wire net.
Mist-Scrubber
Sum parameter – Total Organic Carbon
TOC – Determination in brines
SCA-130-304
The determination in difficult matrices, such
as brines or heavily contaminated wastewaters, presents a special challenge for TOC
analyzers. In the chemical industry, brines
with a salt load (NaCl) of up to 28% are used
for chlor-alkali electrolysis. For this process it
is important to know the TOC content.
The unique feature of this application does
not inherently lie in the conversion of the
carbon components to carbon dioxide, but in
the salt load associated with the matrix. This
leads to higher maintenance needs, as the
salt can crystallize in the combustion system.
■ Kit or high-salt samples
The TOC-L series features a kit for high-salt
samples, which significantly increases the
instrument’s availability. The kit consists of a
combustion tube of a special geometry and a
unique catalyst mixture.
In this application, sample acidification is
carried out with sulfuric acid. Sulfuric acid
modifies the sample matrix. Whereas the
melting point of NaCl ia 801 °C, NaSO4 has
a higher melting point is (888 °C). The
potassium salts of sulfuric acid also have a
significantly higher melting point than those of
hydrochloric acid. This extends the lifetime of
the combustion tube.
Compound
Melting point
NaCl
801°C
KCl
773°C
Na2SO4
888°C
MgCl2
708°C
CaCl2
782°C
K2SO4
1.069°C
Tab. Melting point of different salts
■ Sample preparation
The determination of organic contaminations
in a pure brine (30% sodium chloride
solution) is described below. For such highly
concentrated salt solutions, the principle of
diluting the sample as much as possible
applies. As the required detection limit was at
< 1 mg/L, the samples were diluted with
ultrapure water to a ratio of 1:1. Dilution was
carried out manually in a 50 mL volumetric
flask under the addition of several drops of
concentrated sulfuric acid (25%).
SCA-130-304
Compound
(Concentration)
Brine
solution
(30%)
Dilution
Conc.
1 : 2 diluted with
water (25ml/50ml)
add. 1-2 drops
Sulfuric acid until
pH<7
ca.
15%ig
Initially, a blank value and a control standard
(10 mg/L) were measured, and the NaCl
solution was subsequently injected.
The control standards were tested after 110
and 220 injections of the brine solution,
respectively.
For the analysis a TOC-LCPH equipped with a
kit for high salt loads was used. The system
is calibrated using the automated dilution
function in the range of 0.5 mg/L to 10 mg/L.
Maintenance of the combustion tube and the
catalyst was not necessary after the
measurements were completed. Only the TCslider needed to be cleaned. The figure
above shows the excellent reproducibility’s
and the stability of the measurement. Fig. Multi-point calibration
with dilution function
■ Result
The duplicate determination of the TOC
analysis yielded the following results:
Sample
Brine solution (30%)
Brine solution (30%)
NPOC
[mg/l]
3,6
3,6
RSD
[%]
1,8
1,8
■ Stability test In this test, the long-term stability of the
combustion system was tested. The system
was calibrated to 10 mg/L with an injection
volume of 50 µL.
A 28% NaCl solution was prepared and
spiked with a KHP solution to obtain a 5 mg/L
TOC solution and a 15% sulfuric acid solution
was added.
■ Recommended Analyzer / Configuration
TOC-LCPH
High-Salt-Kit
B-Type-Scrubber
Sum parameter – Total Organic Carbon
TOC – Determination in sodium
hydroxide solution
SCA-130-305
Organic contaminants in basic chemicals may
lead to impurities in the products. Therefore,
quality control of the reactants is necessary.
Several mL of ultrapure water were placed in
a 50 mL volumetric flask. Subsequently, 5 mL
of the concentrated sodium hydroxide was
pipetted into the flask. Finally, concentrated
sulfuric acid was added until the solution has
reached a pH < 2. The flask was then filled
with ultrapure water up to the mark. The
addition of sodium hydroxide, as well as the
addition of sulfuric acid to the water must be
done with the utmost care and caution, as a
violent chemical reaction occurs.
Compound
(Concentration)
The TOC determination in sodium hydroxide
can lead to various problems. The catalyst
and the combustion tube wear out very
rapidly. This, in turn, will lower the sensitivity
at an equally fast rate and leads to very poor
reproducibilities.
NaOH can also absorb CO2 from the
environment. As air contains approximately
400 ppm CO2, direct TC determination in
sodium hydroxide can lead to much higher
values. The NPOC method is, therefore,
recommended for the determination of
organic contaminations in sodium hydroxide.
The sample should also be diluted as much
as possible.
Dilution
1 : 10 diluted
Sodium
hydroxide
solution
(50%)
approx.
(5 ml / 50 ml) add.
5%
1-2 drops Sulfuric
acid until pH<7
+ Sulfuric
(Note: generation of
acid
heat)
Calibration of the TOC-L system was carried
out using the automatic dilution function
within the range of 0.5 mg/L to 10 mg/L.
In the present case, a 50% sodium hydroxide
solution was analyzed. The purity criterion
and the required limit of detection was < 10
mg/L.
■ Sample Preparation
The sample was first manually diluted to a
ratio of 1:10 with ultrapure water and a
suitable amount of acid.
Conz.
[%]
Fig. Multi-point calibration
with dilution function
SCA-130-305
10
9
Signal[mV]
■ Kit for high salt samples
For the determination, a TOC-LCPH was
equipped with a kit for high salt loads. The kit
consists of a special catalyst tube, a special
mixture of various catalyst beads and a
ceramics grid, which replaces the platinum
net.
6
3
0
-1
0
5
10
Zeit[min]
Fig. Example peaks of 50% sodium hydroxide
solution
■ Recommended Analyzer / Configuration
When using the high-salt kit, sample
acidification is carried out with sulfuric acid,
which is used here to modify the sample
matrix. Compared to NaCl with a melting
point of 801 °C, the melting point of NaSO4 is
higher (881 °C) which extends the lifetime of
the combustion tube.
■ Results
The 5% sodium hydroxide can now be
measured using the NPOC method. The
duplicate determination of the sodium
hydroxide yielded the following results.
Sample
Sodium hydroxide
(50%)
Sodium hydroxide
(50%)
NPOC
[mg/l]
RSD
[%]
<10 (8,2)
-
<10 (8,3)
-
The sodium hydroxide met the required purity
criteria of < 10 mg/L TOC.
TOC-L CPH
OCT-L (8-port samples)
High-Salt-Kit
B-Type-Scrubber
Sum parameter – Total Organic Carbon
TOC – Determination in soda solution
SCA-130-306
Impurities in products can be caused by
organic contaminants present in basic
chemicals to. That is a reason why quality
control of the reactants is indispensable.
In
the
determination
of
organic
contaminations
in
concentrated
soda
solutions, various issues must be considered.
In comparison to organic carbon, the soda
solution to be investigated has a very high
inorganic carbon content in the form of
carbonates. In addition, the solution has a
high pH value and tends to absorb carbon
dioxide from the air.
A soda solution must, therefore, be analyzed
using the NPOC method.
In the case described here, a 50% soda
solution was investigated. The required
detection limit was 10 mg/L.
■ Sample preparation
The sample was first manually diluted to a
ratio of 1:10 with ultrapure water and a
corresponding amount of acid. Several mL of
ultrapure water were placed in a 50 mL
volumetric flask. Subsequently, 5 mL of the
concentrated soda solution was pipetted into
the flask. Finally, concentrated sulfuric acid
was added until the solution has reached a
pH < 2.
The flask was then filled with ultrapure water
up to the mark.
Compound
Dilution
Conc.
(Concentration)
Soda
hydroxide
solution
1 : 10 diluted
with water
(5ml/50ml)
(50%)
add. 1-2 drops
Sulfuric acid
until pH<7
Approx.
5%
Caution: During the addition of the sulfuric
acid, the carbonates decompose under a
violent reaction (heat dissipation / gas
formation).
SCA-130-306
Calibration of the TOC-L system was carried
out using the automatic dilution function in the
range of 0.5 mg/L to 10 mg/L.
The higher melting point point of NaSO4 (881
°C) compared to NaCl (801 °C) has a positive
influence on the lifetime of the combustion
tube.
■ Results
The duplicate determination of the soda
solution yielded the following results:
Sample
For the determination, a TOC-LCPH was
equipped with a kit for high salt loads. A
special catalyst tube, a special mixture of
various catalyst beads and a ceramics grid,
which replaces the platinum net are part of
the kit.
RSD
[%]
56,4
7,1
54,8
4,9
10
9
Signal[mV]
Fig. Multi-point calibration
with dilution function
Soda solution
(50%)
Soda solution
(50%)
NPOC
[mg/l]
6
3
0
-1
0
5
10
Zeit[min]
Fig. Peak graphs of a diluted soda solution
(ca.5%)
Sample acidification when using the high-salt
kit, is carried out with sulfuric acid in order to
modify the sample matrix.
■ Recommended Analyzer / Configuration
TOC-L CPH
ASI-L
High-Salt-Kit
B-Type- Scrubber
15
Sum parameter – Total Organic Carbon
TOC – Determination in ammonia or
ammonium salt solutions
SCA-130-307
Basic chemicals may contain organic
contaminants polluting end products. This is
why quality control of the reactants is a must.
In the TOC determination of ammonia water
or concentrated ammonium salt solutions,
various issues must be considered. Ammonia
and some ammonium salts are alkaline. The
catalyst and combustion tube are sensitive to
alkaline media and are subjected to
increased wear.
■ Sample preparation
The ammonium nitrate solution was diluted
with ultrapure water to a ratio of 1:10. Dilution
was carried out manually in a 50 mL
volumetric flask under addition of several
drops of concentrated sulfuric acid (25%).
Compound
(Concentration)
Dilution
Conc.
Ammonium
nitrate
solution
(40%)
1 : 10 diluted
(5 ml / 50 ml)
add. 1-2 drops
Sulfuric acid until
pH<7 (Note:
generation of heat)
Approx.
4%
Calibration of the TOC-L system was
executed using the automatic dilution function
in the range of 0.5 mg/L to 10 mg/L.
The solutions should, therefore, be acidified
and possibly be diluted.
The decomposition during oxidation of the
ammonium or ammonia proceeds to
completion without the formation of residues
on the catalyst. Therefore, it is not necessary
to use a high-salt kit.
In the case described below, the NPOC
content of a 40% ammonium nitrate solution
was determined. The required detection limit
was < 10 mg/L.
Fig. Multi-point calibration
with dilution function
SCA-130-307
■ Results
The
duplicate
determination
of
ammonium nitrate solution yielded
following results:
40
30
Signal[mV]
■ Interferences In addition to CO2 formed from the organic
components, various nitrogen oxides are
formed during the combustion of ammonium
salts or ammonia water. Excessively high
nitrogen levels can lead to the formation of
significant amounts of N2O (nitrous oxide).
Nitrous oxide exhibits absorption bands in the
same IR detection range as CO2 and can,
therefore, be misinterpreted for CO2. In
addition, nitrous oxide can cause tailing and
can affect the peak symmetry.
A B-type scrubber is used to eliminate
possible interference by nitrous oxide. Due to
the high solubility of N2O in water, the gas is
dissolved in the B-type scrubber and will not
reach the detector.
20
10
0
-4
0
7
14
Zeit[min]
Fig. Example peaks of 40% ammonium nitrate
solution
the
the
■ Recommended analyzer / Configuration
Probe Ammonium nitrate solution (40%) Ammonium nitrate solution (40%) NPOC [mg/l] RSD [%] 56,5 0,8 56,7 1,2 TOC-L CPH
OCT-L (8-port sampler)
B-Type- Scrubber
Sum parameter – Total Organic Carbon
TOC – Determination in sodium nitrate
and sodium nitrite
SCA-130-308
Basic chemicals may contain organic
contaminants influencing the quality of
products. Quality control procedures of the
reactants are, therefore, necessary in order to
detect impurities.
For
the
determination
of
organic
contaminations in salts, solutions of these
salts can be prepared and subsequently
measured using a TOC-L analyzer.
Compound
(Concentration)
Sodium nitrate
(>99,9%)
Sodium nitrite
(>99,9%)
Dilution
Weighted Sample
5 g / 50 ml
add. 1-2 drops
Sulfuric acid until
pH<7
Weighted Sample
5 g / 50 ml
add. 1-2 drops
Sulfuric acid until
pH<7
Conz.
approx.
10%
approx.
10%
Caution: Nitrogen
oxide gas is
released
Caution: Nitrite salts react to form of toxic
nitrous gases. Sample preparation should,
therefore, always be carried out under a
hood. The samples should only be removed
from the hood, when no more nitrous gases
escape.
High salt concentrations generally present a
problem for TOC analysis. These salts can
crystallize in the combustion system and lead
to higher maintenance needs.
Calibration of the TOC-L system was done
applying the automatic dilution function in the
range of 0.5 mg/L to 10 mg/L.
In the case described below, the NPOC
content of two salts was determined. The
difficulty was the required detection limit of 10
mg/kg.
■ Sample preparation
For sample preparation, 5 g of both salts
(sodium nitrite and sodium nitrate) were
weighed into a 50 mL volumetric flask and
diluted with ultrapure water. During dilution,
the solutions were acidified with concentrated
sulfuric acid (25%).
Fig. Multi-point calibration
with dilution function
SCA-130-308
■Kit for high-salt samples
The TOC-L series features a kit for high-salt
samples, which significantly increases the
instrument’s availability. The kit consists of a
combustion tube of a special geometry and a
unique catalyst mixture.
■ Results
The duplicate determination of the salt
solutions yielded the following results:
Sample Sodium nitrate (>99,9%) Sodium nitrate (>99,9%) Sodium nitrate (>99,9%) Sodium nitrate (>99,9%) NPOC [mg/kg]
22,8 24,0 <10 (9,0) 10,2 RSD [%] 4,7 6,8 ‐ 5,4 Signal[mV]
10
9
6
3
0
-1
0
5
10
Zeit[min]
15
20
Fig. Example peaks: Sodium nitrate In this application, sample acidification is
carried out with sulfuric acid which is used to
modify the sample matrix. Due to the higher
melting point of NaSO4 (888 °C) compared to
801 °C of NaCl the lifetime of the combustion
tube is longer.
■ Interferences
The combustion of nitrogen compounds can
lead to the formation of nitrous oxide gas.
Nitrous oxide exhibits absorption bands in the
same IR detection range as CO2 and can,
therefore, be misinterpreted for CO2. In
addition, nitrous oxide can cause tailing and
can affect the peak symmetry.
A B-type scrubber is used to eliminate
possible interference by nitrous oxide. Due to
the high solubility of N2O in water, the gas is
dissolved in the B-type scrubber and will not
reach the detector.
■ Recommended Analyzer / Configuration
TOC-LCPH
ASI-L
High-Salt-Kit
B-Type-Scrubber
4. TOC special applications
Due to its informative significance, the
TOC sum parameter is widely applicable.
It mirrors the total concentration of
organically bound carbon or organic
compounds.
can control and calculate interferences
that can be attributed to the matrix.
Various options, kits and modules enable interference-free analyses in a
wide range of applications.
In addition to the environmental, pharmaceutical and chemical industries,
the TOC parameter is used in numerous
other applications. The user’s scientific
curiosity and ingenuity often wants to
solve an analytical problem or simplify
complex analytics, and then finds the
TOC as a key to the answer.
With its TOC analyzers, Shimadzu offers
flexible systems that can be modularly
upgraded using various kits, modules
and options. In this way, the TOC analyzer can be customized to the specific
measurement task.
The TOC parameter can be determined
easily and reliably. The experienced user
The possibility to detect and quantify all
organic compounds within a simple analytical run always leads to new, often
unusual, applications. Some only seem
to be useful for a one-time use while
others seem to revolutionize entire analytical application areas.
Further information can be found in
the individual application notes (for instance ‘TOC determination in algae,
liquid manure or carbon dioxide determination in beer’). In addition to TOC
special applications, there are also
application notes and information on
‘Pharmaceutical industry’, ‘Chemical
Industry’, ‘Environmental analysis’, ‘TOC
in daily practice’ and ‘TOC process analysis.’
Sum parameter – Total Organic Carbon
TOC- determination in algal biomass –
suspension method
SCA-130-401
■Innovative methods
To determine the biomass in the
photobioreactor, a TOC analyzer was used.
The carbon content of the ‘algal soup’ is
directly proportional to the biomass.
The excessive global CO2 emissions from the
burning of fossil fuels (for instance in power
plants) causes the search for climate-friendly
uses of carbon dioxide.
One of the approaches for environmentally
sound recycling is to convert the emitted CO2
into biomass using photobioreactors.
The CO2 gas is introduced into the
photobioreactor in order to be used for the
growth of algae. The biomass, or algae, can
be used in many different application areas:
in the cosmetics industry, the construction
industry, and the food segment, in agriculture
as fertilizer or for energy utilization.
■ Test methods for implementation The efficiency of the photobiorectors and the
yield of growth are continuously monitored.
To this end, various methods are available,
including the determination of dry mass
(gravimetric) or the photometric determination
of chlorophyll (by absorption). These methods
either require a high expenditure in terms of
time and personnel, or they are nonspecific
and inaccurate.
■ TOC Measurement method
Depending on the type of algae used in the
reactor, either the difference method or the
direct method (NPOC) is suitable. In both
cases, one should test which method will
most accurately detect each particular type of
algae. This can be compared with the results
of the reference method.
Information on the analysis:
 calibration of the TC/NPOC and the IC
parameters via the automated dilution
function
 sample is generally measured undiluted
 injection volume: 90 µL
 at least 3 to 5 injections for statistical
confidence
 rinse several times, depending on the
sample
SCA-130-401
■ Sample preparation
The 4 – 10 µm large micro-algae of the
Chlorella vulgaris species can be measured
directly after sampling from the reactor
without any further sample preparation. The
difference method was used for the biomass
determination. The method is suitable for all
other single-cell algae that exhibit a stable
carbon content under different growth
conditions.
Using the difference method, the TC and TIC
were determined and the TOC was
subsequently calculated from these values.
Calibration using the resulting dry mass of the
algae makes it possible to draw conclusions
on the dry biomass content in the sample
from the TOC.
■ Corrrelation
The TOC correlation (algae biomass/TOC)
must be determined for each type of algae
specifically. It can also be calibrated against
the determined dry mass.
the extracellular substances produced by the
algae or released into the culture medium
after the algae have died off. The TOC
determined this way is the carbon content of
the investigated algae. To draw conclusions
on the dry mass yield, the percentage carbon
content in the algae must be determined. Several direct and indirect methods are
available. The most simple and, at the same
time, highly reliable method is to combust the
washed and dried algae in a solid-matter
TOC analyzer. A second method is to filter
the algae, dry them and then determine their
mass. In combination with TOC and
photometry measurements, a correlation
between the TOC value and the algal dry
mass can be determined, which provides
information on the carbon content of the
algae. From the carbon mass fraction and the
TOC value, the dry mass of the algae solution
can be very accurately calculated.
Dry mass – TOC Calibration ■ Recommended analyzer / Configuration
TOC-L CPH
ASI-L (40ml) with stirrer option and external
Sparge-Kit
First, the algae sample is measured and the
TOC is determined. Subsequently, the
sample is filtered through a 0.2 µm syringe
filter and measured again in the TOC
analyzer to be able to distinguish between the
TOC content originating from the algae and
the carbon content possibly originating from
Sum parameter – Total Organic Carbon
SCA-130-402
TOC- determination in liquid manure and
fermentation fluids
– suspension method
Biogas is one of the energy sources of the
future and can be used in the generation and
supply of energy, or it can be fed into the
natural gas networks in the form of
biomethane. The generation of energy from
renewable or regenerative energy sources,
which include water, wind, solar and other
types of biomass, replaces the use of fossil
fuels.
For the production of biogas from, for
instance, various liquid manures or maize
silages, pretreatment methods for liquid
manure and the optimization of the
fermentation process and biogas yield are
investigated.
Fig. Experimental setup to generate bio gas in the
laboratory
■ Efficiency Reactors with various volumes are used for
production testing. The prepared liquid
manure or mixtures of other substrates are
used for fermentation. The generated biogas
is diverted via pipelines, the resulting volume
is pneumatically determined and the gas
composition is analyzed.
To evaluate the efficiency of the reactor and
the method, biogas was analyzed in different
ways. An important parameter is the gas
chromatographic
determination
of
the
methane content. In order to be able to
compare the biogas yield of the various
substrates, the biogas volume or methane
volume was expressed in terms of the
organic dry matter present in the substrate
(Nl/kg ODM). This requires the accurate
determination of the initial concentration of
the organic substance in the liquid manure.
SCA-130-402
For this determination, proven methods are
available. First, the dry matter (DM) of the
liquid manure is determined at 105 °C. The
dried liquid manure is subsequently annealed
to a constant mass at 550 °C in a muffle
furnace. The loss of mass during annealing
corresponds to the organic content of the
liquid manure. The ratio of methane gas
concentration
and
organic
content
corresponds to the biogas production yield
(fermentation) and is a key criterion for the
fermentation of different types of biomass and
for the assessment of the efficiency of
fermentation processes.
■ Innovative methods
In order to avoid long annealing times for the
ODM determination, an alternative method for
the determination of the organic substance
was sought. The TOC suspension method
was considered suitable for this purpose. The
dried sample was weighed into an
Erlenmeyer flask and mixed with hydrochloric
acid to convert the inorganic carbon
compounds, such as carbonates and
hydrocarbonates, to carbon dioxide. In the
next step, a dispersion device was used to
break up and homogenize the suspension.
During this process, most of the generated
carbon dioxide was also removed. The final
solution is subsequently transferred into the
autosampler vials of the analyzer and
automatically analyzed. For this purpose, a
small fraction is injected onto the 720 °C hot
platinum catalyst. The organic substances
are then converted into carbon dioxide and
measured using an NDIR detector.
The advantage of this alternative method lies
in its suitability for automation. This way,
many
samples
can
be
processed
automatically in sequence.
With the possibility of multiple injections, the
method also offers statistical reliability. In the
muffle furnace, a combusted weighed sample
yields an ODM value. The suspensions are
generally analyzed at least four times to
establish a mean value.
■NPOC-Determination
For the determination of the organic content
in liquid manure (duplicate determination from
two different approaches with each 5
separate injections) yielded the following
results:
Liquid manure
(dried and
powdered)
Sample 1
Sample 1
Sample 2
Sample 2
NPOC
[mass.%]
44,1
44,2
44,2
42,5
RSD
[%]
0,8
1,9
1,6
1,4
Signal[mV]
1000
900
600
300
0
-100
0
5
10
Zeit[min]
Fig. NPOC-Peaks of suspension
Fig. Homogenisation of the suspension
15
SCA-130-402
■ TNb-Determination
The TOC determination using catalytic
combustion oxidation allows the simultaneous
measurement of the total bound nitrogen
(TNb), since, in addition to the carbon dioxide
from organic substances, NO is formed from
nitrogen-containing compounds.
For the
conversion of NO to NO2, the measuring gas
ozone was fed to the chemiluminescence
detector connected in-series. The photons
emitted during this reaction are detected and
are used in the calculation of the TNb value.
Nitrogen compounds also play an important
role when it comes to liquid manure.
.
■ Conclusion
The TOC suspension method offers a good
alternative for the fast, straightforward and
accurate analysis of the organic content in
liquid manure samples. The possibility for codetermination of the nitrogen content also
enables users to acquire additional useful
information for the evaluation of liquid manure
samples.
Signal[mV]
100
90
60
30
0
-10
0
5
10
Zeit[min]
15
20
Fig.4: Peak graphs of TN-determination
Simultaneously with the organic content, the
TNb was determined (duplicate determination
from two different approaches with 5 separate
injections each) yielding the following results:
Liquid manure
(dried and
powdered)
Sample 1
Sample 1
Sample 2
Sample 2
TNb [mass.‐%] RSD [%] 1,84 1,80 1,76 1,68 1,5 0,9 2,2 1,4 ■ Recommended Analyzer / Configuration
TOC-L CPN with normal sensitive Catalyst
for TNb-Determination: TNM-L Module
ASI-L (40ml) with stirrer option and external
Sparge-Kit.
Sum parameter – Total Organic Carbon
Carbon dioxide determination in beer
SCA-130-403
Carbon dioxide is an important ingredient in
many soft drinks. This is also the case for
beer. It creates a sparkling and refreshing
(tangy) taste and is important for the
formation of foam.
The CO2 content of a beer affects the
threshold values for various fragrance and
aroma components. In addition, bottling
under CO2 increases the shelf life of beer..
In order to develop a method that does not
have these disadvantages, a TOC analyzer
was used.
■ Innovative methods In this method, the sample (beer) is directly
placed in a 40 mL autosampler vial. 5 mL of a
32% NaOH solution was added to the
autosampler vial to preserve the CO2.
The sample is subsequently added directly to
the autosampler and the IC (inorganic
carbon) content is measured.
In the manual of the ‘central- European
brewery technological analysis commission)’
(MEBAK)
various
methods
for
the
determination of CO2 are listed. These are
generally based on manometric or titrimetric
method, or they are methods that use
specialized detectors.
Disadvantages of these methods are often
the lack of selectivity for CO2 (other gases or
substances are also determined), high
expenditure in terms of personnel and time,
and the lack of possibilities for automation.
Preservation step: -
-
CO + OH
2
→ HCO
3
2-
-
CO + 2 OH
2
→ CO
3
+HO
2
In the TOC analyzer, the sample is injected in
a concentrated phosphoric acid solution
(25%). The CO2 is subsequently released
again and is transferred via the carrier gas to
a CO2-selective NIDR detector where it is
detected.
SCA-130-403
Displacement reaction: (the strong acid
displaces the weak acid from its salt)
-
+
HCO + H
→
3
2-
CO
3
H O + CO
2
2
+
+2H
→ H O + CO
2
2
To calculate the results, the IC function of the
TOC system is calibrated using a sodium
hydrogen carbonate standard in the range of
100 – 1000 mg/L. The dilution of the
individual calibration points is performed
automatically via the dilution function of the
instrument.
dioxide in bottled or canned beer. In this step,
5 mL of a 32% solution of NaOH was directly
added to the freshly opened bottle or can for
preservation.
■ Comparison of the methods
The following graph shows the good
agreement between the TOC method (blue
bars) and the Corning method (green bars).
6,00
5,00
4,00
3,00
2,00
1,00
0,00
■ Advantages of this method
 can be automated to a high degree
 fast
 good reproducibility and high accuracy
(precision)
 multiple determinations from one sample
is possible
 effortless calibration
 simple operation
 highly specific
Using the modern TOC-L software,
evaluation can be carried out automatically or
can be recalculated manually. Another
function enables further processing of the
measurement results. This way the carbon
dioxide content can be directly presented in
the desired dimension. Due to the possibility
for multiple injections, the evaluation contains
all the important statistical quantities
Another sample preparation variant is to be
carried out during the determination of carbon
■ Recommended Analyzer / Configuration
TOC‐L CPH ASI‐L (40ml) 5. TOC in daily practice
As market leader in TOC analysis,
Shimadzu connects tradition with experience. This enables users to profit
from personal support or by attending
seminars and user meetings organized
by Shimadzu. These application-oriented
meetings serve for the exchange of information and experiences.
In this particular field of application
notes, specific sets of subjects ‘TOC in
daily practice’ are listed that are not
covered by one of the special applications. These are subjects that are related
to the TOC parameter, independently of
the matrix.
The wealth of experience in TOC analysis naturally finds its way into the devel-
opment of our TOC systems. Whether
online analyzers or laboratory TOC systems – they all impress by their great
flexibility, high availability, extreme
robustness and stability, simple and
intuitive operation and advanced operating and evaluation software. Many
additional functions facilitate the user’s
work and provide more freedom for other important tasks.
This chapter also applies to the individual modules, kits or options of
Shimadzu’s TOC analyzers. Useful functions are also described.
Further details are available in the individual application notes (for instance
‘TOC determination methods’, ‘Total
nitrogen determination’ or ‘Blank values’). In addition to the information on
‘TOC in daily practice’, there are also
application notes on ‘Pharmaceutical
industry’, ‘Chemical Industry’, ‘TOC special applications’, ‘Environmental analysis’ and ‘TOC process analysis.’
Sum parameter – Total Organic Carbon
TOC – Determination methods according
to EN 1484
SCA-130-501
The EN 1484 standard “Guidelines for the
determination of total organic carbon (TOC)
and dissolved organic carbon (DOC)” defines
various terms and parameters.
■ Definitions according to EN 1484
TC:
Total carbon – the sum of organically
bound and inorganically bound carbon
present in water, including elemental carbon.
TIC: Total inorganic carbon – the sum of
carbon present in water, consisting of
elemental carbon, carbon monoxide, carbon
dioxide (also carbonates and hydrogen
carbonates),
cyanide,
cyanate,
and
thiocyanate. TOC instruments mainly detect
CO2, originating from hydrogen carbonates
and carbonates, just like TIC.
The following graph
parameters are linked:
shows
how
the
TC
TOC
NPOC
IC
POC
■ Determination methods
The TOC can be determined according to
three different methods:
TOC: Total Organic Carbon – organically
bound carbon present in water, bonded to
dissolved or suspended matter. Cyanate,
thiocyanate and elemental carbon are also
determined.
POC: Purgeable Organic Carbon – the TOC
content that is purgeable under the conditions
of this method.
NPOC: Non Purgeable Organic Carbon – the
TOC content that is not purgeable under the
conditions of this method.
■ Difference method
For the difference method, the parameters
TC and IC are measured. The TOC is then
determined by way of calculation.
TC: The analysis of the total organic carbon
is carried out via oxidation (thermal or wetchemical) and subsequent determination of
the resulting carbon dioxide using NDIR
detection.
TIC: Through acidification of the sample
using a mineral acid at room temperature and
subsequent NDIR detection of the expelled
carbon dioxide the inorganic carbon is
detected.
SCA-130-501
The TOC is calculated from the difference
between TC and TIC: TOC = TC - TIC
■ Limitations of the difference method
The inorganic carbon content may not be too
high in comparison to the TOC.
Error propagation can result in a high level of
uncertainty for the calculated TOC value. The
EN 1484 standard recommends that the TOC
value, when using the differential method,
should be higher or equal to the TIC value
(TOC ≥ TIC).
Example:
TC – Value = 100 mg/l (RSD = 2%) ± 2 mg/l
(98 – 102 mg/l)
IC – Value = 98 mg/l (RSD= 2%) ± 1,96 mg/l
(96,04 – 99,96mg/l)
TOC = 2 mg/l ± 3,96mg/l (- 1,96 - 5,96 mg/l)
Due to error propagation, the total error is ±
3.96 mg/L.
According to the difference method, the error
of the total result is larger than the calculated
TOC content! In the worst case, this can
result in a negative TOC value.
■ Addition method
For the addition method, the parameters POC
and NPOC are measured. The TOC is then
calculated.
POC: Degassing of the volatile compounds
with subsequent catalytic combustion at
680°C and determination of the resulting
carbon dioxide using NDIR detection.
NPOC: Measurement of the non-purgeable
organic compounds, after POC analysis
using catalytic combustion at 680°C and
subsequent determination of the resulting
carbon dioxide using NDIR detection.
The TOC is calculated via addition:
TOC = POC + NPOC
■ Direct method
For the direct or NPOC method, it is assumed
that the sample does not contain any
significant amounts of volatile or purgeable
organic compounds. According to this
assumption, the TOC is directly determined
as NPOC.
NPOC: Acidification of the sample using a
mineral acid (for instance HCL) to a pH < 2,
whereby
carbonates
and
hydrogen
carbonates are completely converted to
carbon dioxide. The carbon dioxide is
removed from the sample solution via a
sparge gas. Direct NPOC measurement
(similar to TC measurement) via oxidation to
CO2. Subsequent NDIR detection.
The TOC corresponds to the NPOC:
TOC = NPOC
Sum parameter – Total Organic Carbon
Determination of the purgeable organic
carbon (POC)
SCA-130-502
According to EN 1484, which contains the
instructions for TOC determination, the POC
(purgeable organic carbon) is the TOC
content that can be expelled under the
conditions of this method. This information is
very unspecific and should be described here
in more detail.
The instruments in the TOC-L series can be
extended with an option to include
measurement of the POC parameter. The
core feature of this option is the LiOH trap,
which is placed in the flow line of the
analyzer.
Here, the volatile organic compounds are
converted to CO2 and detected via NDIR
detector.
TOC
NPOC
POC
Fig. The addition method (NPOC + POC)
During the course of the addition method, the
remainder is used for NPOC determination.
However, in the drinking water application or
ultrapure water application, the POC content
is completely negligible. Here, TOC = NPOC
The POC can, nevertheless, play an
important role in wastewaters, particularly in
industrial effluents.
For POC determination, the sample is
aspirated using the TOC-L injection syringe,
acidified with HCL and subsequently purged
using carrier gas. In this step, CO2 originating
from carbonates and hydrogen carbonates as
well as all volatile organic compounds (POC)
are purged from the solution. The LiOH trap
binds the CO2 from the gas mixture
(originating from the TIC). The volatile
compounds pass the trap and reach the
catalyst.
■ Calibration Particular attention should be paid to
calibration of the POC. Standards that are
prepared with volatile, purgeable organic
substances are inherently very unstable. This
is why IC standard solutions (prepared from
carbonates and/or hydrogen carbonates) are
used for POC calibration. Sampling of the IC
solutions for POC determination is carried out
using the TOC-L injection syringe. The IC
solution is acidified in the syringe. The
inorganic substances of the standard solution
are converted to CO2 and transferred to the
NDIR detector using a carrier gas.
SCA-130-502
POC-Peak:
NPOC-Peak:
Fig. POC-Calibration with IC-standard
■ System testing
In POC analysis, it is of great importance that
the LiOH trap functions perfectly. A test
should, therefore, be carried out to confirm
the efficiency of the CO2 trap. This test
should be carried out each working day:
An IC control solution (TIC = 1000 mg/L) is
prepared and analyzed as a POC sample.
For efficient functioning of the LiOH trap, the
POC measuring result must be < 0.1 mg/L.
Result:
TOC=4,05mg/l
POC=4,05mg/l => 100%
NPOC=0mg/l
■ Example of a POC measurement
Sample: Toluene in ultrapure water
Toluene is a compound that is fully
purgeable. In the addition method, the
toluene sample is completely determined as
POC.
POC measuring method:
Injection volume:
Purging time:
800 µL
3 min
■ Recommended Analyzer / Configuration
TOC-LCXX
ASI-L
POC-Option
Sum parameter – Total Organic Carbon
TNb – total bound nitrogen
SCA-130-503
Although nitrogen compounds are essential
for nature and the environment, high nitrogen
depositions can lead to problems. Nitrogen
compounds enter the environment primarily
through agricultural processes. Nitrogencontaining fertilizers constitute the largest
proportion. But nitrogen compounds can also
enter the environment via chemical industrial
processes.
Excessively high concentrations of nitrogen
compounds in the environment can cause
eutrophication of water bodies. Eutrophication
is the process of uninhibited growth of algae
and other organisms due to an excess supply
of nutrients. This overgrowth results in a lack
of oxygen in the water, which can lead to fish
mortality and to the formation of aquatic dead
zones.
■ Total nitrogen TNb
The variety of possible nitrogen compounds
necessitated the definition of a sum
parameter that represents the total nitrogen
compounds. For this purpose, the so-called
TNb (total bound nitrogen) was defined and
standardized.
The TNb is the total nitrogen content of a
sample in the form of ammonium, nitrite,
nitrate, as well as organic compounds. The
TNb does not include dissolved or gaseous
nitrogen (N2). A differentiation between
inorganic and organic nitrogen compounds is,
by definition, not possible.
Bound nitrogen occurs in nearly all waters,
mostly in the form of ammonia, nitrate, nitrite
or organic compounds.
■ Determination according EN 12260 EN 12260 describes the determination of
nitrogen in the form of free ammonia,
ammonium, nitrite, nitrate and organic
compounds that can be converted under the
described oxidative conditions.
SCA-130-503
The conversion of the nitrogen containing
compounds takes place via combustion in an
oxygen atmosphere higher than 700 °C to
nitrogen oxide, which reacts with ozone to
activated nitrogen dioxide (NO2*). In the
subsequent reaction to NO2, light quanta are
emitted (chemiluminescence) that are
measured by the detector.
Subsequently, the gas mixture enters the
chemiluminescence detector, connected in
series, where the nitrogen content is
determined (See Figure below).
■ Simultaneous TN determination using
the TNM-L
Based on the similar oxidation process, the
TNb determination can be carried out
simultaneously with the TOC measurement.
For this application, the TNM-L option is
installed on the top of the main TOC-L
system.
Fig. Simultaneous TOC/TN-Determination
Fig. TOC-L CSH with TNM-L Modul
The benefit is that no additional laboratory
space is required.
For the simultaneous determination, the
sample is injected onto the catalyst at 720 °C.
All carbon atoms present in the sample are
converted to CO2 and, in parallel, the nitrogen
atoms to NO. The gas mixture is then
transported by the carrier gas stream through
the NDIR detector, where the carbon dioxide
content is measured.
It should be noted that an optimal injection
volume must be selected for both
parameters.
■ Recommended Analyzer / Configuration
TOC-L CXX with TNM-L
ASI-L
Sum parameter – Total Organic Carbon
Kit for high-salt samples
SCA-130-504
Samples with high-salt loads generally are a
problem for TOC analysis. The problem is
less the conversion of organic compounds to
CO2 than the effects of the salt on the
catalyst. This leads to higher maintenance
needs, as the salt can crystallize in the
combustion system.
In many applications for the instruments in
the TOC-L and the TOC-4110/4200 series,
the kit for salt-containing samples is an
important component. It consists of a
combustion tube of a special geometry and a
unique mixture of catalyst beads.
While NaCl has a melting point of 801 °C, the
melting point of Na2SO4 is higher (888 °C).
The potassium salts of sulfuric acid also have
a significantly higher melting point than those
of hydrochloric acid. This has a positive effect
on the lifetime of the combustion tube.
Compound
Melting point
NaCl
801°C
KCl
773°C
Na2SO4
888°C
MgCl2
708°C
CaCl2
782°C
K2SO4
1.069°C
Tab. Melting point of different salts
Results indicate that the stability of the
catalyst is increased, and that up to 12 times
the number of samples can be measured
before the catalyst must be exchanged and
the instrument needs servicing.
■ Sample preparation
In this application, sample acidification is
carried out with sulfuric acid which is used to
modify the sample matrix.
Fig. Catalyst filling
SCA-130-504
■ Endurance test
To determine the performance of this option,
a brine solution was measured in a long-term
test. For this purpose, a 28 % NaCl solution
(matrix adapted with a 15 % sulfuric acid
solution and spiked to a 5 ppm TOC solution
using a KPH solution) was injected 220 times.
Initially, a blank value and a control standard
with 10 ppm TOC were measured. The
control standards were tested after 110 and
220 injections, respectively. The injection
volume was 50 µL.
The following figure shows the excellent
reproducibilities and the stability of the
measurement.
Concentratoin
Area
10
50
40
8
30
6
4
20
2
10
0
Area
Concentration[mg/L]
H i g h Sa l t　Conbuti uon　tube 28%N a Cl i n 5mg /LKH P[Inj :50uL A ci d:15%]
0
0
50
100
150
Injections
200
250
Fig. Results of endurance test
■ Related application
The high-salt kit is used for many different
applications in order to keep the maintenance
need for difficult matrices as low as possible.
Examples:
 104 TOC-Determination in seawater
 304 TOC-Determination in brine solution
 306 TOC-Determination in soda solution
 308 TOC-Determination in sodium nitrate
 603 TOC-Determination in chemical
industry
■ Recommended Analyzer / Configuration
TOC-L CXX
ASI-L
Kit for high-salt samples
B-Type Scrubber
(At very high halogen concentrations in the
matrix, the B-type scrubber is recommended.
This scrubber protects the detector cell of the
NDIR detector.)
Sum parameter – Total Organic Carbon
Kit for small sample volumes
SCA-130-505
The instruments of the TOC-L series are
designed to successively analyze many
different types of samples of different
concentrations. For the autosampler, sample
trays for different sample numbers and
sample volumes are available.
■ Small sample volumes
It can also occur, however, that only a few mL
of sample are available. This is usually the
case when there is only little sample
available, the sampling process is complex or
the sample is very valuable. For such cases,
the kit for small sample volumes is available.
The 5 mL syringe body can be exchanged for
a 500 µL syringe in a rapid conversion step.
Moreover, the injection slider has to be
exchanged too.
■ Specification
With this option, automatic dilution,
acidification and sparging is not possible and
the specifications are, therefore, changed as
follows:
To eliminate cross-contamination between
analyses of the different samples, the number
of rinsing steps can be defined in the
software. There is usually enough sample
volume available to rinse the tubing and the
injection system of the TOC-L several times.
Depending on the measuring method,
injection volume, measurement range and
rinsing steps, 10 – 20 mL of the sample is
needed.
Measurement range: TC, IC: to 2,000 mg/L
TN: to 200 mg/L
Injection volume:
150µl maximal
Diameter:
0.2 mm
NPOC-Measurement: In ASI-L with external
Sparge kit
ASI-L:
9ml Rack
■ Example
5 mL sample is sufficient for NPOC
determination using an ASI-L, 9mL vials
(3 injections with 150 µL injection volumes)
Sum parameter – Total Organic Carbon
Kit for manual injection
SCA-130-506
The manual injection kit enables the analysis
of water samples and gases. The sample for
TC determination is directly injected into the
combustion chamber using a µL syringe. This
is interesting for applications where only a
very small sample volume is available.
The kit for small sample volumes is a module
for TOC analyzers that can be used for
automated sample preparation and analysis
of small sample amounts. The methods can
be optimized in such a way that only a few
mL of the sample are required. Optimization
should, however, not be at the expense of the
intermediate rinsing step.
When even smaller amounts than the few
milliliters are available, the TOC-L user can
fall back on the manual injection kit.
For gas samples, a distinction can be made
between total carbon (for instance CO or
CH4) and CO2.
The kit consists of two injection blocks, which
can be easily installed in the TOC system.
One of the injection blocks is used instead of
the IC-port; the other block replaces the TC
injection block.
This conversion does not take longer than
one minute.
■ Specification
For liquid samples:
Measurement range:
Injection volume:
Measurement time:
Reproducibility:
For gas samples:
Measurement range:
Injection volume:
Measurement time:
Reproducibility:
TC, IC: to 20.000 mg/L
150µl maximal
TC, IC: 3 minutes
RSD: 2%
(over 8.000mg/L: 3% )
6ppm to 100% CO2
20µl bis 10mL
2 – 4 Minuten
RSD: 2%
Sum parameter – Total Organic Carbon
Calibration with automatic dilution
function
SCA-130-507
■ Calibration with automatic dilution
function
To create calibration curves, the dilution
function is activated via the wizard:
The core feature of the TOC-L series is the
ISP
module
(Integrated
Sample
Pretreatment). The ISP module consists of an
8-port valve and a syringe with sparging gas
connector. In addition to acidification and
sparging in the syringe, the system enables
automated dilution. This allows for the wide
measuring range, dilutes highly polluted
samples and enables the creation of dilution
series from a stock solution. The various
possibilities offered by the ISP module thus
reduce the time expenditure by the user.
Fig. ISP-Module of TOC-L
series
When filling the data of the calibration points,
the concentration of the standard solution
(stock) is entered first, followed by the
desired calibration curve point. The software
calculates the required dilution factor:
Since fractional factors are allowed, it is
possible to create a 10-point calibration curve
with equidistant concentration intervals from
one standard solution.
SCA-130-507
The following fgure shows the list of
calibration points of a 10-point calibration
curve in the range of 1 to 10 mg/L:
■ Calibration with automatic dilution
function over two decades
In addition, there is the possibility to use
different standard solutions for the dilution.
Calibration was carried out from 1 to 100
mg/L using two standard solutions (10 and
100 mg/L).
The measured calibration curve exhibits a
linear range with a very good correlation
coefficient (r = 0.9995).
Also here, the measured calibration curve
exhibits a linear range with a very good
correlation coefficient (r = 0.9995).
Sum parameter – Total Organic Carbon
Blank value consideration in TOC analysis
SCA-130-508
Water plays a dual role in TOC trace
analysis. On one hand, it is applied as a
measuring medium and consumable in the
TOC analyzer. It is used to prepare standards
and to rinse the instrument. The automatic
dilution function of the TOC-L uses ultrapure
water for dilution of the samples or the
standard solutions for multi-point calibration.
On the other hand, ultrapure water is a
sample type in TOC analysis. In ultrapure
water applications, including the analysis of
water for injection and cleaning validation,
ultrapure water samples are analyzed to
determine their organic impurities.
For the determination of low concentrations at
the trace-level, knowledge on the blank value
is essential. The blank value is usually
composed of several components. First, there
is the instrument blank, secondly residual
concentrations can occur in the solvent and in
the reagents used. The influence of the blank
value is particularly significant in TOC
analysis, as carbon compounds are present
everywhere and a widespread carbon input
can, therefore, not be prevented.
With careful sample preparation and analysis,
this blank value can be minimized and
reliably determined. The blank value
consideration and the analysis of a system
blank value is only useful in very low
concentration ranges of < 1 mg/L.
Purified waters that have been produced
using highly complex water treatment
systems, have different water grades. The
DIN ISO 3696 standard specifies the
requirements and test methods for water for
analytical use and classifies these waters
according to 3 grades.
Parameter Pure water Typ III Pure water Typ II Ultra pure water Typ I Ions, resistance (M.cm) >0,05 >1,0 >18,0 Ions, resistance (µS/cm) < 20 <1,0 <0,055 Organix, TOC (ppb) <200 <50 <10 Pyrogene (EU/ml) NA NA <0,03 Particle >0,2µm (U/ml) NA NA <1 Bacteria (KBE/ml) <1000 <100 <1 Tab 1: specification according to DIN ISO 3696
SCA-130-508
■ Blank value considerations
When, for instance, the NPOC is calibrated in
the lowest concentration ranges, a positive
area value for the zero value of the x-axis
generally results, as well as a positive value
of the y-axis where it intercepts the x-axis.
Both situations only describe the ratio
between the actual blank value and the blank
value when the calibration curve has been
created. To obtain an absolute concentration
value, there is the possibility of zero offset.
The zero offset is a parallel offset of the
calibration curve through the zero point.
Through this offset, the absolute term (b) of
the curve is set to zero and the blank value
(positive intercept) of the calibration is taken
into consideration in the sample analysis.
This positive area value reflects the blank
value. This blank value is, however, not
attributable to a specific factor or a specific
cause but appears as the sum of the various
blank value factors. This sum can consist of
the following:
Total blank value = Σ of
+
Blank value of the instrument
+
Reagent impurity
+
Blank value of the standard
(ultrapure water)
+
Contaminations from the environment
(dust,
contaminations
on
the
glassware, etc.)
The calibration is evaluated according to the
general straight-line equation:
y=m•x+b
y = Peak area
x = TOC – concentration
m = slope of calibration
b = intercept
When a blank sample is now measured
against this curve, the concentration 0 mg/L
is obtained or, if the ultrapure water used is
slightly
cleaner,
even
a
negative
concentration value.
While the concentration in ultrapure water for
the preparation of standard includes a blank
value, the carbon concentration in an
ultrapure water sample only reflects the
actual TOC concentration of the sample.
In short: dilution water has a blank value, a
sample does not have a blank value.
SCA-130-508
■ Instrument blank value
Due to the ubiquity of certain compounds,
potential minute leaks in the instrument and
possibly persistent deposits or biofilms, can
lead to area values that originate from the
instrument itself and not from the measured
sample. To determine this value, the ‘blank
check’ procedure can be performed:
For this purpose, the system (TOC-LCPH)
carries out an automatic analysis of
circulating ultrapure water. The resulting
condensation is collected in a suitable
container inside the instrument. As soon as
enough condensed water is available, the
water is circulated, i.e. it is injected again.
This procedure is carried out 50 times and it
can, therefore, be assumed that the final
determined area value corresponds to the
actual instrument blank value.
■ Reagents – blank value
Reagents, such as hydrochloric acid, often
stand unobserved and unintentionally next to
the instrument for months and absorb vast
amounts of organic carbon from the
environment
(‘from
a
blank
value
perspective’). For the determination of such
reagent blank values, the standard addition
method is suitable.
■ Contaminations from the environment
At last, the blank value is discussed that can
arise from everywhere in the environment
and can enter the analysis from various
sources. People and their industrial
landscapes are the source of a large variety
of organic carbon compounds. Humans
themselves consist of 18.2 % organic carbon
and lose, for example, 1 – 2 g skin particles
per day. These generally settle in the form of
house dust.
In addition to carbon originating from our
own bodies, carbon sources present in
cosmetics or toiletries such as soaps,
deodorants, perfumes, after-shaves skin
creams, ointments, plays an important role.
Also the laboratory harbors large sources of
organic carbon compounds.
Note: The determination of the instrument
blank value is also suitable for intensive
cleaning of the flow lines and for the ‘breaking
in’ a newly built-in catalyst. As this is a very
time
consuming
method,
it
should
preferentially be carried out overnight.
Room air contains numerous pollutants that
can easily bind to dust particles and can
therefore also be present in house dust.
Finally, it should not be overlooked that room
air contains approximately 0.4 vol% / 0.06
mass% (400 / 600 ppm) CO2.
Sum Parameter – Total Organic Carbon
TOC – Measurement principle
Catalytic combustion at 680°C
SCA-130-509
■TOC-Measurement principle
The organic carbon compound is oxidized by
combustion to carbon dioxide. The carrier gas
(transporting the CO2) is cooled and
dehumidified and passed through a halogen
scrubber into the cell of the NDIR (Non
Dispersive Infrared) detector where the CO2
is detected. The NDIR outputs a detection
signal which generates a peak.
Salt interference at the detection cell from the
salt melt products may impact the quality and
accuracy of the data. Maintenance time is
also increased due to the extended cool
down and reheating time required based on
the higher combustion temperature.
■ Shimadzu TOC method
Shimadzu
developed
the
catalytically
oxidation at 680°C and uses peak area for
integration. This temperature is lower as the
melting points of some salts:
Compound
NaCl
KCl
Na2SO4
MgCl2
CaCl2
Melting point
801 °C
773 °C
888 °C
782°C
782 °C
Tab. Melting points of different salts
The deactivation of the catalyst and the
corrosion of the combustion tube are
minimized. In total the maintenance request
is lower as using higher temperature. On the
other hand the platinum catalyst ensures a
complete oxidation of all organic compounds.
■ Peak detection
In the past high temperatures (up to 1000°C)
were necessary because the first TOC
instruments use the peak height for
integration. Due to this the conversion to CO2
must be instantaneous to keep the peak as
narrow and sharp as possible.
■ Disadvantage of high temperature
The very high combustion temperature has
the disadvantage of high levels of
maintenance (deactivation of catalyst,
corrosion of combustion tube and detector
cell) due to the salt melt products.
SCA-130-509
■ Recovery rates with 680°C combustion
technique
Compound
Compound
Prepared
[mg/L]
Measured
[mg/L]
Recovery
[%]
Urea
200.0
203.0
101.5
Urea
2.000
1.986
99.3
Ethylurea
100.0
102.3
102.3
Thiourea
200.0
201.8
100.9
Thiourea
2.000
1.973
98.7
Prepared
[mg/L]
Measured
[mg/L]
Recovery
[%]
200.0
201.2
100.6
50.0
49.8
99.6
166.2
166.6
100.2
172.5
173.0
100.3
Dimethylformamide
139.5
141.5
101.4
Nicotinic
acid
200.0
198.5
99.3
Glucose
200.0
200.4
100.2
Nicotinic
acid
2.000
1.932
96.6
Sucrose
200.0
197.5
98,8
200.0
199.3
99.7
Sucrose
50.0
49.9
99.8
Sulfanilic
acid
Sucrose
2.000
1.968
98.4
Sulfanilic
acid
2.000
1.969
98.5
Fructose
50.0
49.9
99.8
53.0
100.6
55.0
56.0
101.8
Sulfosuccin
ic acid
52.7
Dodecylbenzene
sulfonic acid
10.10
10.55
104.5
L-glutamic
acid
50.0
50.1
100.2
Cyanuric
acid
8.36
8.61
103.0
Tartaric
acid
50.0
49.8
99.6
Acrylamide
200.0
197.1
98.6
Citric acid
50.0
49.6
99.2
Pyridine
hydrochloride
Tannine
47.0
47.4
100.9
2.000
1.983
99.2
Lignin
48.3
47.7
98.8
Albumin
44.5
44.1
99.1
Pyridine
hydrochloride
Humic acid
44.7
45.3
101.3
200.0
202.3
100.4
Caffeine
50.0
49.5
99.0
Quinine
hydrochloric
1,10Phenanthroline
50.0
49.7
99.4
Quinine
hydrochloric
2.000
2.008
100.8
Catechin
50.0
49.1
98.2
100.0
98.6
98.6
1,4-Benzoquinone
100.0
100.4
100.4
Cellulose
(insoluble)
3.00
2.99
99.7
Sodium
acetate
100.0
98.3
98.3
Polystyrene
(insoluble)
Nicotinamide
200.0
198.9
99,5
Nicotinamide
100.0
101.3
101.3
Nicotinamide
2.000
1.993
99.7
Ethanol
2-Propanol
1-Pentanol
1-Hexanol
Note: The recovery rate is effected by sample
preparation, instrument condition and surrounding
circumstances!
6. TOC process analysis
Laboratory analysis yields comprehensive and detailed results but, depending
on circumstances, requires much time –
time that is often not available during
ongoing operations. For this reason,
operators of different types of plants
increasingly use sum parameters, which
can also be determined continuously
during the actual process. Contrary to
conventional laboratory analysis, it is
not an individual substance but an
entire substance group that is determined here. In process waters from the
chemical industry, sum parameters serve
as an indicator of contaminations or all
kinds of substance loads.
One of the most important chemical
sum parameters is the TOC. It is a measure of the organic pollution level or the
organic constituents in the matrix.
Particularly during process control it is
important to obtain fast, continuous and
informative data on the organic pollution levels of waters. TOC process analysis offers this possibility. The sample is
fed continuously to the instrument for
subsequent measurement. The instrument sends the analytical data to the
control room, which can react promptly
to any possible process changes.
One of the most important attributes of
a TOC process analyzer is its versatility.
Since a TOC process system is not available ‘off-the-shelf’, each measurement
task must be customized to the particular measuring problem, the matrix and
the sampling location. The analyzer
must be tailored to the specific measuring task and not vice versa.
Various types of sampling systems as
well as kits and options for the many
diverse applications are therefore essential. In addition to suitable equipment,
robustness and service life of the instru-
ment (availability) are of major importance. After all, it is important that the
analyzer can measure autonomously
and transmit reliable analytical data.
protocol is available. An optional web
browser enables access to the instrument from any network-connected computer.
With its TOC-4200 series, Shimadzu
offers an online analyzer that, with its
various modules, kits and options, provides exactly the flexibility needed and
can be equipped for the most diverse
applications. A selection of sampling
techniques is available: from a singlestream sampler to a sample exchanger
for six different sample streams, without
or with homogenizer for water containing particles.
More information can be found in various application notes (for instance ‘TOC
determination in the paper industry,
sewage treatment plants and power
plants’). In addition to TOC process
analysis, information is also available on
the application areas ‘Pharmaceutical
industry’, ‘Chemical Industry’, ‘TOC special applications’, ‘TOC in daily practice’
and ‘Environmental analysis.’
The TOC-4200 stands out not only in
terms of its robustness but also by its
reliability. The TOC-4200 already integrates the most advanced communication channels to the control room. In
addition to the conventional communication modes, a Modbus communication
Sum parameter – Total Organic Carbon
Continuous TOC/TN determination in
wastewater treatment plants
SCA-130-601
A uniform definition of wastewater does not
yet exist. Wastewater is often used as a
generic term for sludge, industrial wastewater
and infiltration water. The contents of
wastewater can vary widely depending on
their origin, and a distinction is made between
oxygen consuming compounds, nutrients,
harmful substances and contaminants [1].
Wastewater treatment is carried out to
eliminate wastewater contents and to restore
the natural water quality.
In municipal wastewater treatment plants,
biological processes are used in aerobic and
anaerobic wastewater treatment for the
degradation of organically highly polluted
wastewater. These plants use microbiological
degradation processes. A stable nutrient ratio
(carbon : nitrogen : phosphorus) is a
precondition for an optimal degradation
capacity of the microorganisms. Therefore, it
is important to continuously monitor the inflow
to the sewage plant. The treated effluent
leaving the sewage plant must also be
monitored continuously. Only when the limit
levels of the German Wastewater Ordinance
are reached, the water may flow back.
■ TOC determination in wastewater
Two oxidation techniques are now commonly
used in TOC analysis:
 catalytic combustion, where carbon
compounds are converted into CO2
using
a
catalyst
under
high
temperatures
with
subsequent
detection of the resulting CO2 using
an NDIR detector
 wet chemical oxidation, which applies
a combination of UV irradiation and
persulfate for oxidation. The resulting
CO2 is either detected via an NDIR
detector or using a conductivity
detector.
For TOC determination in wastewater,
catalytic combustion has become the method
of choice based on its higher oxidation
potential, especially for particles. Regarding
TOC methods, the German Wastewater
Ordinance states the following: “A TOC
system with thermal-catalytic combustion
(minimum temperature of 670 oC) must be
used.”
■ TOC-4200
The TOC-4200 is a high-performance
analyzer with catalytic combustion at 680 °C.
Depending on the sample characteristics,
three TOC analysis methods can be selected
(direct method, difference method, addition
method). The automatic dilution function
enables TOC analyses up to 20,000 mg/L. In
addition, the TOC-4200 can be extended with
a module for measuring the total bound
nitrogen (TN). An automatic dilution function
and the self-calibration option allow a virtually
independent operation of the measuring
system.
SCA-130-601
■ Sampling
An analysis system is only as good as the
sample preparation preceding it. Various
sample preparation systems are available for
the 4200 series, which can be optimally tuned
to the individual application area. When
sewage plant inlet and outlet are to be
measured using the same instrument, the
sample
stream
switcher
is
used.
■ Remote control
The measuring instruments can be started
and calibrated from a control station, and a
selection between the different measuring
streams is possible. Numerous alarm and
status signals simplify detection of exceeded
limit levels and indicate the need for
maintenance. In addition to the conventional
communication
modes,
a
Modbus
communication channel is available. An
optional web browser enables a ‘view’ of the
instrument from any networked computer.
The software counts consumables such as
acids and pure water for dilution, and emits a
signal to the measuring station for refilling the
consumables.
■ Recommended analyzer / Configuration
TOC-4200
Multi-Stream suspended solids sampling unit
Acid Rinse option
Fig. Multi-Stream switcher
The sample enters the sample chamber via a
strainer, where it is homogenized through a
rotating knife before it is transferred to the
instrument for analysis. This way, even
samples containing large amounts of
particulate matter can be measured without
any problems. After sampling, the chamber
and the strainer are cleaned with rinsing
water. Depending on the application, the
rinsing water can be acidified in order to
prevent the growth of algae. The rinsing
function prevents any carry-over effects when
changing sample streams. The measuring
program can be individually selected for each
sample stream. In addition, the user can
freely choose the measuring sequence of the
sample streams.
[1] Source: Wikipedia
Sum parameter – Total Organic Carbon
TOC process analysis in the paper
industry
SCA-130-602
Paper manufacturing requires the use of
water for various processes (suspension and
transport of the pulp, cooling water, sieve and
felt cleaning, system cleaning). Although the
water circulation in paper mills has been
systematically optimized in recent years due
to water conservation, the paper industry still
requires large quantities of fresh water for the
production of paper. Wherever fresh water is
consumed, large amounts of wastewater are
also produced and these must be
continuously monitored. The wastewater from
paper and pulp mills is usually highly polluted
with organic carbon compounds. The many
different products with various coatings, for
instance
specialty
papers,
produce
wastewater of widely varying compositions
and concentrations.
Fig.Example of four different sample streams in the
paper industry
The online analysis of these types of
wastewater is a major challenge for the
analyzer and for the sample preparation
■ TOC-4200
The TOC-4200 is a high-performance
analyzer with catalytic combustion at 680 °C.
Depending on the sample characteristics,
three TOC analysis methods can be selected
(differential method, addition method, direct
method). The automatic dilution function
enables TOC analyses up to 20,000 mg/L. In
addition, the TOC-4200 can be extended with
a module for measuring the total bound
nitrogen (TN).
An automatic dilution function and the selfcalibration
option
allow
a
virtually
independent operation of the measuring
system. The measuring instruments can be
started and calibrated from one measuring
station and a selection between the different
measuring streams is possible. Numerous
alarm and status signals simplify detection of
exceeded limit levels and indicate the need
for maintenance.
In addition to the conventional communication
modes, a Modbus communication channel is
available. An optional web browser enables a
‘view’ of the instrument from any networked
computer.
SCA-130-602
■ Sampling
The sometimes highly fibrous wastewater can
clog tubes and pipes. Various mechanisms
and options are available to prevent clogging.
The wastewater streams are sequentially
transported to the analyzer using various
valves. Following each sample feed to the
analyzer, the valves and tubes are flushed
with fresh water and an acid rinse. This
prevents the formation of buildup in the
valves. The acid rinse and water rinse are
controlled by the TOC analyzer.
The rinsing function prevents any carry-over
effects when changing sample streams. The
measuring program can be individually
selected for each sample stream. In addition,
the user can freely chose the measuring
sequence of the sample streams.
Fig.: Multi-stream suspended solids pretreatment unit
■ Recommended analyzer / Configuration
Fig. Acid Rinse option to clean tubes and
sampling system
After the sample has passed the respective
valve, it enters the sample chamber via a
strainer where it is homogenized using a
rotating knife before it is transferred to the
instrument for analysis. This way, even
samples containing large amounts of
particulate matter can be measured without
any problems. After sampling, the chamber
and the strainer are cleaned with acidified
rinsing water.
TOC-4200
Multi-stream suspended solid pretreatment
unit
Acid rinse system
Sum parameter – Total Organic Carbon
Continuous TOC determination in the
chemical industry
SCA-130-603
The high demand for many different products
from the chemical industry and the required
efficiency of the manufacturing processes
often requires around-the-clock production.
This results in huge amounts of wastewater.
This water mostly originates from flowing
water bodies.
Industrial wastewaters must be pretreated
before being discharged into public sewage
treatment plants. Direct discharge into water
bodies requires an extensive cleaning
process. This is why many large companies
or industrial parks operate their own
wastewater treatment plants.
■ TOC determination in industrial
wastewater
The TOC content (Total Organic Carbon) is a
measure of the concentration of organically
bound carbon and is an indication of the
pollution level by organic compounds in
wastewater. This is why the TOC is often
used in sewage treatment plants as
measuring parameter to monitor and optimize
the treatment process and to calculate
pollution levels. The matrix in industrial
effluents can vary greatly and can – prior to
sewage treatment –
be polluted with high salt loads. For TOC
determination
in
wastewater,
catalytic
combustion has become the method of
choice based on its higher oxidation potential,
especially for particles.
■ Are high salt loads a problem?
During thermal catalytic combustion of the
test sample, the dissolved salts crystallize.
High salt loads can lead to pollution of the
catalyst, or even clogging of the system.
Maintenance
measures
(for
instance
exchanging the catalyst) would then be
required in order to render the instrument
operational again. Of course, it is desirable to
keep the maintenance intervals as long as
possible.
■TOC-4200
The TOC-4200 offers various possibilities to
keep the maintenance needs for highly
polluted samples at a minimum. The TOC4200 with catalytic combustion at 680 °C is a
high-performance analyzer. This temperature
is lower than the melting point of sodium
chloride and will, therefore, prevent
deactivation of the active centers of the
catalyst by a melt. The use of a platinum
catalyst ensures the complete conversion of
the organic compounds to CO2. The highly
sensitive NDIR detector allows small injection
volumes (typically 20 - 50 µL) that reduce the
absolute sample input onto the catalyst. A
further reduction can be achieved using the
integrated dilution function.
SCA-130-603
This can take place when measurement
values are exceeded or can be applied
permanently. In this case, the user specifies
the desired dilution factor in the selected
method.
■ Kit for high-salt samples
For the continuous TOC determination of
samples with high salt loads (> 10 g/L),
Shimadzu has developed a salt kit. The
combustion tube has a special shape and
uses two different catalyst beads. This
combination prevents crystallization that can
lead to clogging of the system.
■ TOC-4200 in daily practice
To verify the robustness and the reliability of
the TOC-4200 during practical operation, the
analyzer has been subjected to an endurance
test in a German chemical park. For three
months, the TOC-4200 had to stand the test
under the most difficult conditions at one
measuring station. The wastewater under
investigation was alkaline (pH ≥ 12) and
highly saline (conductivity 4 ≥ mS/cm).
The software enables planning of various
automatic maintenance and calibration tasks.
This way, automatic calibration of the
measuring method was programmed to take
place every 48 hours and automatic
regeneration of the catalyst twice a week.
Sampling took place in the counterflow mode
with backflushing in order to prevent clogging.
■ Results of the practice test
As described in the test, a sample was
collected every 4 minutes over a period of
three months, and subsequently diluted,
acidified and analyzed. After three months a
total of approximately 27,000 measurements
was achieved. . Within this period, the
instrument was automatically calibrated 45
times and the catalyst was regenerated
nearly 25 times. These functions can be
easily programmed via a calendar on the
touch screen. The calibration function
gradients remained stable over the entire
time period.
Fig. Diagram of 27.000 Measurement results (three
months)
The test did not require any catalyst
exchange or a single maintenance operation.
There was also no instrument or software
failure or any other component failure. In
short: the TOC-4200 has successfully passed
the endurance test.
Fig. TOC-4200 on site
This is why the instrument was equipped with
a kit for salt-containing samples. In addition,
the automatic dilution function was used to
dilute the samples (including the matrix).
■ Recommended analyzer / Configuration
TOC-4200
Kit for high-salt samples
Sum parameter – Total Organic Carbon
Continuous condensate monitoring using
the TOC-4200
SCA-130-604
When applying TOC determination to
condensates, few particles are usually
expected, but here as well, it is better to be
on the safe side with the higher oxidation
potential offered by catalytic combustion. It is
important to be able to quickly and reliably
detect every possible organic contamination.
Due to the low pollution level of the sample,
the catalyst remains stable over a long time
span, whereby the need for maintenance is
relatively low.
The chemical and petrochemical industry
uses superheated steam as energy carrier for
the supply of energy needed in various
thermal processing steps. Superheated
steam is usually generated from ultrapure
water, which prevents damage to the boilers.
In order to use as little water as possible, the
reflux condensate is redirected to the boiler. It
is, therefore, important to ensure that the
condensate is free from organic pollutants.
■ TOC determination in condensate
The TOC parameter provides information on
organic pollution. The TOC can be easily
determined and is easy to implement in
process analysis. Two oxidation techniques
are now commonly used in TOC analysis:
 Catalytic combustion, where carbon
compounds are converted into CO2
using
a
catalyst
under
high
temperatures
with
subsequent
detection of the resulting CO2 using
an NDIR detector
 Wet chemical oxidation, which uses a
combination of UV irradiation and
persulfate for oxidation. The resulting
CO2 is either detected via an NDIR
detector or a via conductivity detector.
■ TOC-4200
The high-performance TOC-4200 analyzer
applies catalytic combustion at 680 °C. Three
TOC analysis methods can be selected
depending on the sample characteristics:
differential method, addition method, direct
method. Due to the automatic dilution
function TOC analyses up to 20,000 mg/L are
possible. In order to measure the total bound
nitrogen (TN), the TOC-4200 can be
extended with a specific module.
The self-calibration option and an automatic
dilution
function
enable
a
virtually
independent operation of the measuring
system which can be started and calibrated
from one measuring station. The different
measuring streams can be selected.
SCA-130-604
Numerous status and alarm signals simplify
detection of exceeded limit levels and
indicate the need for maintenance.
A
Modbus
communication
channel
complements
the
conventional
communication modes. An optional web
browser gives access to the instrument from
any networked computer.
■ Sampling
For the 4200 series, various sample
preparation systems are available, which can
be optimally tuned to the individual
application area. As condensates are
homogeneous samples (in contrast to
wastewater), an extra sample preparation
step is not necessary. Two sampling systems
are, therefore, suitable:
 an overflow tube, from which the sample
is automatically drawn.
 filling the sampling chamber through a
strainer (50 Mesh), in case the sample
does contain particles that need to be
removed
prior
to
measurement.
Compressed air empties the chamber and
cleans the strainer.
Fig. Sampling
■ TOC measuring method
TOC determination is often carried out via the
NPOC method,
whereby the inorganic carbon content
(carbonates and hydrogen carbonates) is
removed prior to the actual analysis. For this
purpose, the sample is drawn from the
continuous sample stream into a syringe and
automatically acidified via the 8-port valve
(pH 2).
Using the sparging gas connection, the CO2
formed (from the carbonates and hydrogen
carbonates) is purged from the sample. The
remaining solution containing the organic
components
is
subsequently
injected
(septum-free) into the oxidation unit using the
sliding valve technique. The syringe and 8port valve allows automatic dilution and
creation of calibration curves.
■ TOC measurement in the condensate
The system is calibrated using a 2-point
calibration curve, blank water and 2 mg/L.
This is realized using a standard catalyst and
an injection volume of 200 µL. Typical
measuring values are around 0.2 mg/L.
The measuring values of 275 consecutive
measurements of a condensate monitoring
are presented in the Figure below:
The mean value is 0.208 mg/L with a
standard deviation of 0.006 mg/L. The results
show that the required detection limit of 0.05
mg/L presents no problem.
■ Recommended analyzer / Configuration
TOC-4200
Backwash Strainer Sampling unit
For information about Shimadzu, and to contact your local office, please visit our
Web site at www.shimadzu.eu
Shimadzu Europa GmbH
European Headquarters
Albert-Hahn-Str. 6 -10 · D-47269 Duisburg
Tel.: +49 - (0)203 - 76 87-0
Fax: +49 - (0)203 - 76 66 25
shimadzu@shimadzu.eu
www.shimadzu.eu
TOC Application Handbook
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